Using chroma quantization parameter in video coding

ABSTRACT

An example method of video processing includes performing a conversion between a video comprising one or more coding units and a bitstream representation of the video. The bitstream representation conforms to a format rule that specifies that chroma quantization parameters are included in the bitstream representation at a coding unit level or a transform unit level according to the format rule.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/US2020/055332, filed on Oct. 13, 2020, which claims the priorityto and benefits of International Patent Application No.PCT/CN2019/111115, filed on Oct. 14, 2019. All the aforementioned patentapplications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

This patent document relates to video coding techniques, devices andsystems.

BACKGROUND

Currently, efforts are underway to improve the performance of currentvideo codec technologies to provide better compression ratios or providevideo coding and decoding schemes that allow for lower complexity orparallelized implementations. Industry experts have recently proposedseveral new video coding tools and tests are currently underway fordetermining their effectivity.

SUMMARY

Devices, systems and methods related to digital video coding, andspecifically, to management of motion vectors are described. Thedescribed methods may be applied to existing video coding standards(e.g., High Efficiency Video Coding (HEVC) or Versatile Video Coding)and future video coding standards or video codecs.

In one representative aspect, the disclosed technology may be used toprovide a method for video processing. This method includes determining,for a conversion between a chroma block of a video and a bitstreamrepresentation of the video, applicability of a deblocking filterprocess to at least some samples at an edge of the chroma block based ona mode of joint coding of chroma residuals for the chroma block. Themethod also includes performing the conversion based on the determining.

In another representative aspect, the disclosed technology may be usedto provide a method for video processing. This method includesdetermining, for a conversion between a current block of a video and abitstream representation of the video, a chroma quantization parameterused in a deblocking filtering process applied to at least some samplesat an edge of the current block based on information of a correspondingtransform block of the current block. The method also includesperforming the conversion based on the determining.

In another representative aspect, the disclosed technology may be usedto provide a method for video processing. This method includesperforming a conversion between a current block of a video and abitstream representation of the video. During the conversion, a firstchroma quantization parameter used in a deblocking filtering processapplied to at least some samples along an edge of the current block isbased on a second chroma quantization parameter used in a scalingprocess and a quantization parameter offset associated with a bit depth.

In another representative aspect, the disclosed technology may be usedto provide a method for video processing. This method includesperforming a conversion between a video comprising one or more codingunits and a bitstream representation of the video. The bitstreamrepresentation conforms to a format rule that specifies that chromaquantization parameters are included in the bitstream representation ata coding unit level or a transform unit level according to the formatrule.

In another representative aspect, the disclosed technology may be usedto provide a method for video processing. This method includesperforming a conversion between a block of a video and a bitstreamrepresentation of the video. The bitstream representation conforms to aformat rule specifying that whether a joint coding of chroma residualsmode is applicable to the block is indicated at a coding unit level inthe bitstream representation.

In another representative aspect, the disclosed technology may be usedto provide a method for video processing. This method includesperforming a conversion between a video unit and a coded representationof the video unit, wherein, during the conversion, a deblocking filteris used on boundaries of the video unit such that when a chromaquantization parameter (QP) table is used to derive parameters of thedeblocking filter, processing by the chroma QP table is performed onindividual chroma QP values.

In another representative aspect, the disclosed technology may be usedto provide another method for video processing. This method includesperforming a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein the chromaQP offsets are at picture/slice/tile/brick/subpicture level.

In another representative aspect, the disclosed technology may be usedto provide another method for video processing. This method includesperforming a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein informationpertaining to a same luma coding unit is used in the deblocking filterand for deriving a chroma QP offset.

In another representative aspect, the disclosed technology may be usedto provide another method for video processing. This method includesperforming a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein anindication of enabling usage of the chroma QP offsets is signaled in thebitstream representation.

In another representative aspect, the disclosed technology may be usedto provide another method for video processing. This method includesperforming a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein the chromaQP offsets used in the deblocking filter are identical of whether JCCRcoding method is applied on a boundary of the video unit or a methoddifferent from the JCCR coding method is applied on the boundary of thevideo unit.

In another representative aspect, the disclosed technology may be usedto provide another method for video processing. This method includesperforming a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein a boundarystrength (BS) of the deblocking filter is calculated without comparingreference pictures and/or a number of motion vectors (MVs) associatedwith the video unit at a P side boundary with reference pictures of thevideo unit at a Q side boundary.

Further, in a representative aspect, an apparatus in a video systemcomprising a processor and a non-transitory memory with instructionsthereon is disclosed. The instructions upon execution by the processor,cause the processor to implement any one or more of the disclosedmethods.

Additionally, in a representative aspect, a video decoding apparatuscomprising a processor configured to implement any one or more of thedisclosed methods.

In another representative aspect, a video encoding apparatus comprisinga processor configured to implement any one or more of the disclosedmethods.

Also, a computer program product stored on a non-transitory computerreadable media, the computer program product including program code forcarrying out any one or more of the disclosed methods is disclosed.

The above and other aspects and features of the disclosed technology aredescribed in greater detail in the drawings, the description and theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of an overall processing flow of a blockingdeblocking filter process.

FIG. 2 shows an example of a flow diagram of a Bs calculation.

FIG. 3 shows an example of a referred information for Bs calculation atCTU boundary.

FIG. 4 shows an example of pixels involved in filter on/off decision andstrong/weak filter selection.

FIG. 5 shows an example of an overall processing flow of deblockingfilter process in VVC.

FIG. 6 shows an example of a luma deblocking filter process in VVC.

FIG. 7 shows an example of a chroma deblocking filter process in VVC

FIG. 8 shows an example of a filter length determination for sub PUboundaries.

FIG. 9A shows an example of center positions of a chroma block.

FIG. 9B shows another example of center positions of a chroma block.

FIG. 10 shows examples of blocks at P side and Q side.

FIG. 11 shows examples of usage of a luma block's decoded information.

FIG. 12 is a block diagram of an example of a hardware platform forimplementing a visual media decoding or a visual media encodingtechnique described in the present document.

FIG. 13 shows a flowchart of an example method for video coding.

FIG. 14A shows an example of Placement of CC-ALF with respect to otherloop filters (b) Diamond shaped filter.

FIG. 14 b shows an example of Placement of CC-ALF with respect toDiamond shaped filter.

FIG. 15 is a block diagram that illustrates an example video codingsystem.

FIG. 16 is a block diagram that illustrates an encoder in accordancewith some embodiments of the present disclosure.

FIG. 17 is a block diagram that illustrates a decoder in accordance withsome embodiments of the present disclosure.

FIG. 18 is a block diagram of an example video processing system inwhich disclosed techniques may be implemented.

FIG. 19 is a flowchart representation of a method for video processingin accordance with the present technology.

FIG. 20 is a flowchart representation of another method for videoprocessing in accordance with the present technology.

FIG. 21 is a flowchart representation of another method for videoprocessing in accordance with the present technology.

FIG. 22 is a flowchart representation of another method for videoprocessing in accordance with the present technology.

FIG. 23 is a flowchart representation of yet another method for videoprocessing in accordance with the present technology.

DETAILED DESCRIPTION 1. Video Coding in HEVC/H.265

Video coding standards have evolved primarily through the development ofthe well-known ITU-T and ISO/IEC standards. The ITU-T produced H.261 andH.263, ISO/IEC produced MPEG-1 and MPEG-4 Visual, and the twoorganizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4Advanced Video Coding (AVC) and H.265/HEVC standards. Since H.262, thevideo coding standards are based on the hybrid video coding structurewherein temporal prediction plus transform coding are utilized. Toexplore the future video coding technologies beyond HEVC, Joint VideoExploration Team (JVET) was founded by VCEG and MPEG jointly in 2015.Since then, many new methods have been adopted by JVET and put into thereference software named Joint Exploration Model (JEM). In April 2018,the Joint Video Expert Team (JVET) between VCEG (Q6/16) and ISO/IEC JTC1SC29/WG11 (MPEG) was created to work on the VVC standard targeting at50% bitrate reduction compared to HEVC.

2.1. Deblocking Scheme in HEVC

A deblocking filter process is performed for each CU in the same orderas the decoding process. First, vertical edges are filtered (horizontalfiltering), then horizontal edges are filtered (vertical filtering).Filtering is applied to 8×8 block boundaries which are determined to befiltered, for both luma and chroma components. 4×4 block boundaries arenot processed in order to reduce the complexity.

FIG. 1 illustrates the overall processing flow of deblocking filterprocess. A boundary can have three filtering status: no filtering, weakfiltering and strong filtering. Each filtering decision is based onboundary strength, Bs, and threshold values, β and t_(C).

Three kinds of boundaries may be involved in the filtering process: CUboundary, TU boundary and PU boundary. CU boundaries, which are outeredges of CU, are always involved in the filtering since CU boundariesare always also TU boundary or PU boundary. When PU shape is 2N×N (N>4)and RQT depth is equal to 1, TU boundary at 8×8 block grid and PUboundary between each PU inside CU are involved in the filtering. Oneexception is that when the PU boundary is inside the TU, the boundary isnot filtered.

2.1.1. Boundary Strength Calculation

Generally speaking, boundary strength (Bs) reflects how strong filteringis needed for the boundary. If Bs is large, strong filtering should beconsidered.

Let P and Q be defined as blocks which are involved in the filtering,where P represents the block located in left (vertical edge case) orabove (horizontal edge case) side of the boundary and Q represents theblock located in right (vertical edge case) or above (horizontal edgecase) side of the boundary. FIG. 2 illustrates how the Bs value iscalculated based on the intra coding mode, existence of non-zerotransform coefficients and motion information, reference picture, numberof motion vectors and motion vector difference.

Bs is calculated on a 4×4 block basis, but it is re-mapped to an 8×8grid. The maximum of the two values of Bs which correspond to 8 pixelsconsisting of a line in the 4×4 grid is selected as the Bs forboundaries in the 8×8 grid.

In order to reduce line buffer memory requirement, only for CTUboundary, information in every second block (4×4 grid) in left or aboveside is re-used as depicted in FIG. 3 .

2.1.2. β and t_(C) Decision

Threshold values β and t_(C) which involving in filter on/off decision,strong and weak filter selection and weak filtering process are derivedbased on luma quantization parameter of P and Q blocks, QP_(P) andQP_(Q), respectively. Q used to derive β and t_(C) is calculated asfollows. Q=((QP_(P)+QP_(Q)+1)>>1).

A variable β is derived as shown in Table 1, based on Q. If Bs isgreater than 1, the variable t_(C) is specified as Table 1 with Clip3(0,55, Q+2) as input. Otherwise (BS is equal or less than 1), the variablet_(C) is specified as Table 1 with Q as input.

TABLE 1 Derivation of threshold variables β and t_(C) from input Q Q 0 12 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 β 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 6 7 8 tc 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 Q 19 20 21 22 23 2425 26 27 28 29 30 31 32 33 34 35 36 37 β 9 10 11 12 13 14 15 16 17 18 2022 24 26 28 30 32 34 36 tc 1 1 1 1 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 Q 38 3940 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 β 38 40 42 44 46 48 5052 54 56 58 60 62 64 64 64 64 64 tc 5 5 6 6 7 8 9 9 10 10 11 11 12 12 1313 14 142.1.3. Filter on/Off Decision for 4 Lines

Filter on/off decision is done for four lines as a unit. FIG. 4illustrates the pixels involving in filter on/off decision. The 6 pixelsin the two red boxes for the first four lines are used to determinefilter on/off for 4 lines. The 6 pixels in two red boxes for the second4 lines are used to determine filter on/off for the second four lines.

If dp0+dq0+dp3+dq3<β, filtering for the first four lines is turned onand strong/weak filter selection process is applied. Each variable isderived as follows.

dp0=|p_(2,0)−²*p_(1,0)+p_(0,0)|, dp3=|p_(2,3)−2*p_(1,3)+p_(0,3)|,dp4=p_(2,4)−2*p_(1,4)+p_(0,4)|, dp7=p_(2,7)−2*p_(1,7)+p_(0,7)|

dq0=|q_(2,0)−2*q_(1,0)+q_(0,0)|, dq3=|q_(2,3)−2*q_(1,3)+q_(0,3)|,dq4=|q_(2,4)−2*q_(1,4)+q_(0,4)|, dq7=|q_(2,7)−2*q_(1,7)+g_(0,7)|

If the condition is not met, no filtering is done for the first 4 lines.Additionally, if the condition is met, dE, dEp1 and dEp2 are derived forweak filtering process. The variable dE is set equal to 1. Ifdp0+dp3<(β+(β>>1))>>3, the variable dEp1 is set equal to 1. Ifdq0+dq3<(β+(β>>1))>>3, the variable dEq1 is set equal to 1.

For the second four lines, decision is made in a same fashion withabove.

2.1.4. Strong/Weak Filter Selection for 4 Lines

After the first four lines are determined to filtering on in filteron/off decision, if following two conditions are met, strong filter isused for filtering of the first four lines. Otherwise, weak filter isused for filtering. Involving pixels are same with those used for filteron/off decision as depicted in FIG. 4 .

1) 2*(dp0+dq0)<(β>>2), |p3₀−p0₀|+|q0₀−q3₀|<(β>>3) andp0₀−q0₀|<(5*t_(C)+1)>>1

2) 2*(dp3+dq3)<(β>>2), |p3₃−p0₃|+q0₃−q3₃<(β>>3) and|p0₃−q0₃|<(5*t_(C)+1)>>1

As a same fashion, if following two conditions are met, strong filter isused for filtering of the second 4 lines. Otherwise, weak filter is usedfor filtering.

1) 2*(dp4+dq4)<(β>>2), |p3₄−p0₄|+|p0₄−q3₄|<(β>>3) and|p0₄−q0₄|<(5*t_(C)+1)>>1

2) 2*(dp7+dq7)<(β>>2), |p3₇−p0₇|+|q0₇−q3₇|<(β>>3) and|p0₇−q0₇|<(5*t_(C)+1)>>1

2.1.4.1. Strong Filtering

For strong filtering, filtered pixel values are obtained by followingequations. Itis worth to note that three pixels are modified using fourpixels as an input for each P and Q block, respectively.p ₀′=(p ₂+2*p ₁+2*p ₀+2*q ₀ +q ₁+4)>>3q ₀′=(p ₁+2*p ₀+2*q ₀+2*q ₁ +q ₂+4)>>3p ₁′=(p ₂ +p ₁ +p ₀ +q ₀+2)>>2q ₁′=(p ₀ +q ₀ +q ₁ +q ₂+2)>>2p ₂′=(2*p ₃+3*p ₂ +p ₁ +p ₀ +q ₀+4)>>3q ₂′=(p ₀ +q ₀ +q ₁+3*q ₂+2*q ₃+4)>>32.1.4.2. Weak Filtering

Let's define Δ as follows.Δ=(9*(q ₀ −p ₀)−³*(q ₁ −p ₁)+8)>>4When abs(Δ) is less than t_(C)*10,Δ=Clip3(−t _(C) ,t _(C),Δ)p ₀′=Clip1_(Y)(p ₀+Δ)q ₀′=Clip1_(Y)(q ₀−Δ)If dEp1 is equal to 1,Δp=Clip3(−(t _(C)>>1),t _(C)>>1,(((p ₂ +p ₀+1)>>1)−p ₁+Δ)>>1)p ₁′=Clip1_(Y)(p ₁ +Δp)If dEq1 is equal to 1,Δq=Clip3(−(t _(C)>>1),t _(C)>>1,(((q ₂ +q ₀+1)>>1)−q ₁−Δ)>>1)q ₁′=Clip1_(Y)(q ₁ +Δq)

It is worth to note that maximum two pixels are modified using threepixels as an input for each P and Q block, respectively.

2.1.4.3. Chroma Filtering

Bs of chroma filtering is inherited from luma. If Bs>1 or if codedchroma coefficient existing case, chroma filtering is performed. Noother filtering decision is there. And only one filter is applied forchroma. No filter selection process for chroma is used. The filteredsample values p₀′ and q₀′ are derived as follows.Δ=Clip3(−t _(C) ,t _(C),(((((q ₀ −p ₀)<2)+p ₁ −q ₁+4)>>3))p ₀′=Clip1_(C)(p ₀+Δ)q ₀′=Clip1_(C)(q ₀−Δ)2.2 Deblocking Scheme in VVC

In the VTM6, deblocking filtering process is mostly the same to those inHEVC. However, the following modifications are added.

A) The filter strength of the deblocking filter dependent of theaveraged luma level of the reconstructed samples.

B) Deblocking t_(C) table extension and adaptation to 10-bit video.

C) 4×4 grid deblocking for luma.

D) Stronger deblocking filter for luma.

E) Stronger deblocking filter for chroma.

F) Deblocking filter for subblock boundary.

G) Deblocking decision adapted to smaller difference in motion.

FIG. 5 depicts a flowchart of deblocking filters process in VVC for acoding unit.

2.2.1. Filter Strength Dependent on Reconstructed Average Luma

In HEVC, the filter strength of the deblocking filter is controlled bythe variables β and t_(C) which are derived from the averagedquantization parameters qP_(L). In the VTM6, deblocking filter controlsthe strength of the deblocking filter by adding offset to qP_(L)according to the luma level of the reconstructed samples if the SPS flagof this method is true. The reconstructed luma level LL is derived asfollow:LL=((p _(0,0) +p _(0,3) +q _(0,0) +q _(0,3))>>2)/(1<<bitDepth)  (3-1)where, the sample values p_(i,k) and q_(i,k) with i=0 . . . 3 and k=0and 3 can be derived. Then LL is used to decide the offsetqpOffsetbasedon the threshold signaled in SPS. After that, the qP_(L), which isderived as follows, is employed to derive the β and t_(C).qP_(L)=((Qp_(Q)+Qp_(P)+1)>>1)+qpOffset  (3-2)where Qp_(Q) and Qp_(P) denote the quantization parameters of the codingunits containing the sample q_(0,0) and p_(0,0), respectively. In thecurrent VVC, this method is only applied on the luma deblocking process.2.2.2. 4×4 Deblocking Grid for Luma

HEVC uses an 8×8 deblocking grid for both luma and chroma. In VTM6,deblocking on a 4×4 grid for luma boundaries was introduced to handleblocking artifacts from rectangular transform shapes. Parallel friendlyluma deblocking on a 4×4 grid is achieved by restricting the number ofsamples to be deblocked to 1 sample on each side of a vertical lumaboundary where one side has a width of 4 or less or to 1 sample on eachside of a horizontal luma boundary where one side has a height of 4 orless.

2.2.3. Boundary Strength Derivation for Luma

The detailed boundary strength derivation could be found in Table 2. Theconditions in Table 2 are checked sequentially.

TABLE 2 Boundary strength derivation Conditions Y U V P and Q are BDPCM0 N/A N/A P or Q is intra 2 2 2 It is a transform block edge, and P or Qis CIIP 2 2 2 It is a transform block edge, and P or Q has non-zerotransform 1 1 1 coefficients It is a transform block edge, and P or Q isJCCR N/A 1 1 P and Q are in different coding modes 1 1 1 One or more ofthe following conditions are true: 1 N/A N/A 1. P and Q are both IBC,and the BV distance >= half-pel in x- or y-di 2. P and Q have differentref pictures*, or have different number of MVs 3. Both P and Q have onlyone mv, and the MV distance >= half -pel in x- or y-dir 4. P has two MVspointing to two different ref pictures, and P and Q have same refpictures in the list 0, the MV pair in the list 0 or list 1 has adistance >= half-pel in x- or y-dir 5. P has two MVs pointing to twodifferent ref pictures, and P and Q have different ref pictures in thelist 0, the MV of P in the list 0 and the MV of Q in the list 1 have thedistance >= half-pel in x- or y-dir, or the MV of Pin the list 1 and theMV of Q in the list 0 have the distance >= half-pel in x- or y-dir 6.Both P and Q have two MVs pointing to the same ref pictures, and both ofthe following two conditions are satisfied: The MV of P in the list 0and the MV of Q in the list 0 has a distance >= half-pel in x- or y-diror the MV of P in the list 1 and the MV of Q in the list 1 has adistance >= half-pel in x- or y-dir The MV of P in the list 0 and the MVof Q in the list 1 has a distance >= half-pel in x- or y-dir or the MVof P in the list 1 and the MV of Q in the list 0 has a distance >=half-pel in x- or y-dir *Note: The determination of whether thereference pictures used for the two coding sublocks are the same ordifferent is based only on which pictures are referenced, without regardto whether a prediction is formed using an index into reference picturelist 0 or an index into reference picture list 1, and also withoutregard to whether the index position within a reference picture list isdifferent. Otherwise 0 0 02.2.4. Stronger Deblocking Filter for Luma

The proposal uses a bilinear filter when samples at either one side of aboundary belong to a large block. A sample belonging to a large block isdefined as when the width>=32 for a vertical edge, and when height>=32for a horizontal edge.

The bilinear filter is listed below.

Block boundary samples pi for i=0 to Sp−1 and qi for j=0 to Sq−1 (pi andqi follow the definitions in HBEVC deblocking described above) are thenreplaced by linear interpolation as follows:p _(i)′=(f _(i)*Middle_(s,t)+(64−f _(i))*P _(s)+32)>>6), clipped to p_(i) ±tcPD_(i)q _(j)′=(g _(j)*Middle_(s,t)+(64−g _(j))*Q _(s)+32)>>6), clipped to q_(j) ±tcPD_(j)where tcPDt_(i) and tcPD_(j) term is a position dependent clippingdescribed in Section 2.2.5 and g_(j), f_(i), Middle_(s,t), P_(s) andQ_(s) are given below:

Sp, Sq f_(i) = 59 − i * 9, can also be described as f = {59, 50, 41, 32,23, 14, 5} 7, 7 g_(j) = 59 − j * 9, can also be described as g = {59,50, 41, 32, 23, 14, 5} (p side: 7, Middle_(7, 7) = (2 * (p_(o) +q_(o)) + p₁ + q₁ + p₂ + q₂ + p₃ + q₃ + p₄ + q side: 7) q₄ + p₅ + q₅ +p₆ + q₆ + 8) >> 4 P₇ = (p₆ + p₇ + 1) >> 1, Q₇ = (q₆ + q₇ + 1) >> 1 7, 3f_(i) = 59 − i * 9, can also be described as f = {59, 50, 41, 32, 23,14, 5} (p side: 7 g_(j) = 53 − j * 21, can also be described as g = {53,32, 11} q side: 3) Middle_(7, 3) = (2 * (p_(o) + q_(o)) + q₀ + 2 * (q₁ +q₂) + p₁ + q₁ + p₂ + p₃ + p₄ + p₅ + p₆ + 8) >> 4 P₇ = (p₆ + p₇ + 1) >>1, Q₃ = (q₂ + q₃ + 1) >> 1 3, 7 g_(j) = 59 − j * 9, can also bedescribed as g = {59, 50, 41, 32, 23, 14, 5} (p side: 3 f_(i) = 53 − i *21, can also be described as f = {53, 32, 11} q side: 7) Middle_(3.7) =(2 * (q_(o) + p_(o)) + p₀ + 2 * (p₁ + p₂) + q₁ + p₁ + q₂ + q₃ + q₄ +q₅ + q₆ + 8) >> 4 Q₇ = (q₆ + q₇ + 1) >> 1, P₃ = (p₂ + p₃ + 1) >> 1 7, 5g_(j) = 58 − j * 13, can also be described as g = {58, 45, 32, 19, 6} (pside: 7 f_(i) = 59 − i * 9, can also be described as f = {59, 50, 41,32, 23, 14, 5} q side: 5) Middle7, 5 = (2 * (p_(o) + q_(o) + p₁ + q₁) +q₂ + p₂ + q₃ + p₃ + q₄ + p₄ + q₅ + q₅ + 8) >> 4 Q₅ = (q₄ + q₅ + 1) >> 1,P₇ = (p₆ + p₇ + 1) >> 1 5, 7 g_(j) = 59 − j * 9, can also be describedas g = {59, 50, 41, 32, 23, 14, 5} (p side: 5 f_(i) = 58 − i * 13, canalso be described as f = {58, 45, 32, 19, 6} q side: 7) Middle5, 7 =(2 * (q_(o) + p_(o) + p₁ + q₁) + q₂ + p₂ + q₃ + p₃ + q₄ + p₄ + q₅ + p₅ +8) >> 4 Q₇ = (q₆ + q₇ + 1) >> 1, P₅ = (p₄ + p₅ + 1) >> 1 5, 5 g_(j) = 58− j * 13, can also be described as g = {58, 45, 32, 19, 6} (p side: 5f_(i) = 58 − i * 13, can also be described as f = {58, 45, 32, 19, 6} qside: 5) Middle5, 5 = (2 * (q_(o) + p_(o) + p₁ + q₁ + q₂ + p₂) + q₃ +p₃ + q₄ + p₄ + 8) >> 4 Q₅ = (q₄ + q₅ + 1) >> 1, P₅ = (p₄ + p₅ + 1) >> 15, 3 g_(j) = 53 − j * 21, can also be described as g = {53, 32, 11} (pside: 5 f_(i) = 58 − i * 13, can also be described as f = {58, 45, 32,19, 6} q side: 3) Middle5, 3 = (q_(o) + p_(o) + p₁ + q₁ + q₂ + p₂ + q₃ +p₃ + 4) >> 3 Q₃ = (q₂ + q₃ + 1) >> 1, P₅ = (p₄ + p₅ + 1) >> 1 3, 5 g_(j)= 58 − j * 13, can also be described as g = {58, 45, 32, 19, 6} (p side:3 f_(i) = 53 − i * 21, can also be described as f = {53, 32, 11} q side:5) Middle3, 5 = (q_(o) + p_(o) + p₁ + q₁ + q₂ + p₂ + q₃ + p₃ + 4) >> 3Q₅ = (q₄ + q₅ + 1) >> 1, P₃ = (p₂ + p₃ + 1) >> 12.2.5. Deblocking Control for Luma

The deblocking decision process is described in this sub-section.

Wider-stronger luma filter is filters are used only if all of theCondition1, Condition2 and Condition 3 are TRUE.

The condition 1 is the “large block condition”. This condition detectswhether the samples at P-side and Q-side belong to large blocks, whichare represented by the variable bSidePisLargeBlk and bSideQisLargeBlkrespectively. The bSidePisLargeBlk and bSideQisLargeBlk are defined asfollows.bSidePisLargeBlk=((edge type is vertical and p ₀ belongs to CU withwidth >=32)∥(edge type is horizontal and p ₀ belongs to CU with height>=32))?TRUE:FALSEbSideQisLargeBlk=((edge type is vertical and q ₀ belongs to CU withwidth >=32)∥(edge type is horizontal and q ₀ belongs to CU with height>=32))?TRUE:FALSE

Based on bSidePisLargeBlk and bSideQisLargeBlk, the condition 1 isdefined as follows.Condition1=(bSidePisLargeBlk∥bSidePisLargeBlk)?TRUE:FALSE

Next, if Condition 1 is true, the condition 2 will be further checked.First, the following variables are derived:

dp0, dp3, dq0, dq3 are first derived as in HEVC if (p side is greaterthan or equal to 32)  dp0 = ( dp0 + Abs( p_(5,0) − 2 * p_(4,0) + p_(3,0)) + 1 ) >> 1  dp3 = ( dp3 + Abs( p_(5,3) − 2 * p_(4,3) + p_(3,3) ) + 1) >> 1 if (q side is greater than or equal to 32)  dq0 = ( dq0 + Abs(q_(5,0) − 2 * q_(4,0) + q_(3,0) ) + 1 ) >> 1  dq3 = ( dq3 + Abs( q_(5,3)− 2 * q_(4,3) + q_(3,3) ) + 1 ) >> 1dpq0, dpq3, dp, dq, d are then derived as in HEVC.

Then the condition 2 is defined as follows.Condition2=(d<β)?TRUE:FALSEWhere d=dp0+dq0+dp3+dq3, as shown in section 2.1.4.

If Condition1 and Condition2 are valid itis checked if any of the blocksuses sub-blocks:

If(bSidePisLargeBlk)  If(mode block P == SUBBLOCKMODE)    Sp =5  else   Sp =7 else  Sp = 3 If(bSideQisLargeBlk)   If(mode block Q ==SUBBLOCKMODE)     Sq =5   else     Sq =7 else   Sq = 3

Finally, if both the Condition 1 and Condition 2 are valid, the proposeddeblocking method will check the condition 3 (the large blockStrongfilter condition), which is defined as follows. In the Condition3StrongFilterCondition, the following variables are derived:

dpq is derived as in HEVC. sp3 = Abs(p3 − p0 ), derived as in HEVC if (pside is greater than or equal to 32)   if(Sp==5)    sp3 = ( sp3 + Abs(p5 − p3 ) + 1) >> 1   else    sp3 = ( sp3 + Abs( p7 − p3 ) + 1) >> 1 sq3= Abs( q0 − q3 ), derived as in HEVC if (q side is greater than or equalto 32)  If(Sq==5)   sq3 = ( sq3 + Abs( q5 − q3 ) + 1) >> 1  else   sq3 =( sq3 + Abs( q7 − q3 ) + 1) >> 1

As in HEVC derive, StrongFilterCondition=(dpq is less than (β>>2),sp3+sq3 is less than (3*β>>5), and Abs(p0−q0) is less than(5*tC+1)>>1)?TRUE:FALSE

FIG. 6 depicts the flowchart of luma deblocking filter process.

2.2.6. Strong Deblocking Filter for Chroma

The following strong deblocking filter for chroma is defined:p ₂′=(3*p ₃+2*p ₂ +p ₁ +p ₀ +q ₀+4)>>3p ₁′=(2*p ₃ +p ₂+2*p ₁ +p ₀ +q ₀ +q ₁+4)>>3p ₀′=(p ₃ +p ₂ +p ₁+2*p ₀ +q ₀ +q ₁ +q ₂+4)>>3

The proposed chroma filter performs deblocking on a 4×4 chroma samplegrid.

2.2.7. Deblocking Control for Chroma

The above chroma filter performs deblocking on a 8×8 chroma sample grid.The chroma strong filters are used on both sides of the block boundary.Here, the chroma filter is selected when both sides of the chroma edgeare greater than or equal to 8 (in unit of chroma sample), and thefollowing decision with three conditions are satisfied. The first one isfor decision of boundary strength as well as large block. The second andthird one are basically the same as for HEVC luma decision, which areon/off decision and strong filter decision, respectively.

FIG. 7 depicts the flowchart of chroma deblocking filter process.

2.2.8. Position Dependent Clipping

The proposal also introduces a position dependent clipping tcPD which isapplied to the output samples of the luma filtering process involvingstrong and long filters that are modifying 7, 5 and 3 samples at theboundary. Assuming quantization error distribution, it is proposed toincrease clipping value for samples which are expected to have higherquantization noise, thus expected to have higher deviation of thereconstructed sample value from the true sample value.

For each P or Q boundary filtered with proposed asymmetrical filter,depending on the result of decision making process described in Section2.2, position dependent threshold table is selected from Tc7 and Tc3tables that are provided to decoder as a side information:Tc7={6,5,4,3,2,1,1};Tc3={6,4,2};tcPD=(SP==3)?Tc3:Tc7;tcQD=(SQ==3)?Tc3:Tc7;

For the P or Q boundaries being filtered with a short symmetricalfilter, position dependent threshold of lower magnitude is applied:

Tc3 {3,2,1};

Following defining the threshold, filtered p′i and q′i sample values areclipped according to tcP and tcQ clipping values:p″ _(i)=clip3(p′ _(i) +tcP _(i) ,p′ _(i) −tcP _(i) ,p′ _(i));q″ _(j)=clip3(q′ _(j) +tcQ _(j) ,q′ _(j) −tcQ _(j) ,q′ _(j));where p′_(i) and q′_(i) are filtered sample values, pθ_(i) and q″_(j)are output sample value after the clipping and tcP_(i) tcP_(i) areclipping thresholds that are derived from the VVC tc parameter and tcPDand tcQD. Term clip3 is a clipping function as it is specified in VVC.2.2.9. Sub-Block Deblocking Adjustment

To enable parallel friendly deblocking using both long filters andsub-block deblocking the long filters is restricted to modify at most 5samples on a side that uses sub-block deblocking (AFFINE or ATMVP) asshown in the luma control for long filters. Additionally, the sub-blockdeblocking is adjusted such that that sub-block boundaries on an 8×8grid that are close to a CU or an implicit TU boundary is restricted tomodify at most two samples on each side.

Following applies to sub-block boundaries that not are aligned with theCU boundary.

If(mode block Q == SUBBLOCKMODE && edge!=0){  if (!(implicitTU && (edge== (64 / 4))))   if (edge == 2 ∥ edge == (orthogonalLength − 2) ∥ edge== (56 / 4) ∥   edge == (72 / 4))     Sp = Sq = 2;    else     Sp = Sq =3;  else    Sp = Sq = bSideQisLargeBlk? 5:3 }

Where edge equal to 0 corresponds to CU boundary, edge equal to 2 orequal to orthogonalLength-2 corresponds to sub-block boundary 8 samplesfrom a CU boundary etc. Where implicit TU is true if implicit split ofTU is used. FIG. 8 show the flowcharts of determination process for TUboundaries and sub-PU boundaries.

Filtering of horizontal boundary is limiting Sp=3 for luma, Sp=1 andSq=1 for chroma, when the horizontal boundary is aligned with the CTUboundary.

2.2.10. Deblocking Decision Adapted to Smaller Difference in Motion

HEVC enables deblocking of a prediction unit boundary when thedifference in at least one motion vector component between blocks onrespective side of the boundary is equal to or larger than a thresholdof 1 sample. In VTM6, a threshold of a half luma sample is introduced toalso enable removal of blocking artifacts originating from boundariesbetween inter prediction units that have a small difference in motionvectors.

2.3. Combined Inter and Intra Prediction (CHIP)

In VTM6, when a CU is coded in merge mode, if the CU contains at least64 luma samples (that is, CU width times CU height is equal to or largerthan 64), and if both CU width and CU height are less than 128 lumasamples, an additional flag is signalled to indicate if the combinedinter/intra prediction (CIIP) mode is applied to the current CU. As itsname indicates, the CIIP prediction combines an inter prediction signalwith an intra prediction signal. The inter prediction signal in the CIIPmode P_(inter) is derived using the same inter prediction processapplied to regular merge mode; and the intra prediction signal P_(intra)is derived following the regular intra prediction process with theplanar mode. Then, the intra and inter prediction signals are combinedusing weighted averaging, where the weight value is calculated dependingon the coding modes of the top and left neighbouring blocks as follows:

-   -   If the top neighbor is available and intra coded, then set        isIntraTop to 1, otherwise set isIntraTop to 0;    -   If the left neighbor is available and intra coded, then set        isIntraLeft to 1, otherwise set isIntraLeft to 0;    -   If (isIntraLeft+isIntraLeft) is equal to 2, then wt is set to 3;    -   Otherwise, if (isIntraLeft+isIntraLeft) is equal to 1, then wt        is set to 2;    -   Otherwise, set wt to 1.

The CIIP prediction is formed as follows:P _(CIIP)=((4−wt)*P _(inter) +wt*P _(intra)+2)>>22.4. Chroma QP Table Design in VTM-6.0

In some embodiments, a chroma QP table is used. In some embodiments, asignalling mechanism is used for chroma QP tables, which enables that itis flexible to provide encoders the opportunity to optimize the tablefor SDR and HDR content. It supports for signalling the tablesseparately for Cb and Cr components. The proposed mechanism signals thechroma QP table as a piece-wise linear function.

2.5. Transform Skip (TS)

As in HEVC, the residual of a block can be coded with transform skipmode. To avoid the redundancy of syntax coding, the transform skip flagis not signalled when the CU level MTS_CU_flag is not equal to zero. Theblock size limitation for transform skip is the same to that for MTS inJEM4, which indicate that transform skip is applicable for a CU whenboth block width and height are equal to or less than 32. Note thatimplicit MTS transform is set to DCT2 when LFNST or MIP is activated forthe current CU. Also the implicit MTS can be still enabled when MTS isenabled for inter coded blocks.

In addition, for transform skip block, minimum allowed QuantizationParameter (QP) is defined as 6*(internalBitDepth−inputBitDepth)+4.

2.6. Joint Coding of Chroma Residuals (JCCR)

In some embodiments, the chroma residuals are coded jointly. The usage(activation) of a joint chroma coding mode is indicated by a TU-levelflag tu_joint_cbcr_residual_flag and the selected mode is implicitlyindicated by the chroma CBFs. The flag tu_joint_cbcr_residual_flag ispresent if either or both chroma CBFs for a TU are equal to 1. In thePPS and slice header, chroma QP offset values are signalled for thejoint chroma residual coding mode to differentiate from the usual chromaQP offset values signalled for regular chroma residual coding mode.These chroma QP offset values are used to derive the chroma QP valuesfor those blocks coded using the joint chroma residual coding mode. Whena corresponding joint chroma coding mode (modes 2 in Table 3) is activein a TU, this chroma QP offset is added to the applied luma-derivedchroma QP during quantization and decoding of that TU. For the othermodes (modes 1 and 3 in Table 3 Table 3 Reconstruction of chromaresiduals. The value CSign is a sign value (+1 or −1), which isspecified in the slice header; resJointC[ ][ ] is the transmittedresidual), the chroma QPs are derived in the same way as forconventional Cb or Cr blocks. The reconstruction process of the chromaresiduals (resCb and resCr) from the transmitted transform blocks isdepicted in Table 3. When this mode is activated, one single jointchroma residual block (resJointC[x][y] in Table 3) is signalled, andresidual block for Cb (resCb) and residual block for Cr (resCr) arederived considering information such as tu_cbf_cb, tu_cbf_cr, and CSign,which is a sign value specified in the slice header.

At the encoder side, the joint chroma components are derived asexplained in the following. Depending on the mode (listed in the tablesabove), resJointC{1,2} are generated by the encoder as follows:

-   -   If mode is equal to 2 (single residual with reconstruction Cb=C,        Cr=CSign*C), the joint residual is determined according to        resJointC[x][y]=(resCb[x][y]+CSign*resCr[x][y])/2.    -   Otherwise, if mode is equal to 1 (single residual with        reconstruction Cb=C, Cr=(CSign*C)/2), the joint residual is        determined according to        resJointC[x][y]=(4*resCb[x][y]+2*CSign*resCr[x][y])/5.    -   Otherwise (mode is equal to 3, i.e., single residual,        reconstruction Cr=C, Cb=(CSign*C)/2), the joint residual is        determined according to        resJointC[x][y]=(4*resCr[x][y]+2*CSign*resCb[x][y])/5.

TABLE 3 Reconstruction of chroma residuals. The value CSign is a signvalue (+1 or −1), which is specified in the slice header, resJointC[ ][] is the transmitted residual. tu_cbf_cb tu_cbf_cr reconstruction of Cband Cr residuals mode 1 0 resCb[ x ][ y ] = resJointC[ x ][ y ] 1 resCr[x ][ y ] = ( CSign * resJointC[ x ][ y ] ) >> 1 1 1 resCb[ x ][ y ] =resJointCf x ][ y ] 2 resCr[ x ][ y ] = CSign * resJointC[ x ][ y ] 0 1resCb[ x ][ y ] = 3 ( CSign * resJointC[ x ][ y ] ) >> 1 resCr[ x ][ y ]= resJointC[ x ][ y ]

DifferentQPs are utilized are the above three modes. For mode 2, the QPoffset signaled in PPS for JCCR coded block is applied, while for othertwo modes, it is not applied, instead, the QP offset signaled in PPS fornon-JCCR coded block is applied.

The corresponding specification is as follows:

8.7.1 Derivation Process for Quantization Parameters

The variable Qp_(Y) is derived as follows:Qp_(Y)=((qP_(Y_PRED)+CuQpDeltaVal+64+2*QpBdOffset_(Y))%(64+QpBdOffset_(Y)))−QpBdOffset_(Y)  (8-933)The luma quantization parameter Qp′_(Y) is derived as follows:Qp′_(Y)=Qp_(Y)+QpBdOffset_(Y)  (8-934)When ChromaArrayType is not equal to 0 and treeType is equal toSINGLE_TREE or DUAL_TREE_CHROMA, the following applies:

-   -   When treeType is equal to DUAL_TREE_CHROMA, the variable Qp_(Y)        is set equal to the luma quantization parameter Qp_(Y) of the        luma coding unit that covers the luma location (xCb+cbWidth/2,        yCb+cbHeight/2).    -   The variables qP_(Cb), qP_(Cr) and qP_(CbCr) are derived as        follows:        qPi _(Chroma)=Clip3(−QpBdOffset_(C),63,Qp_(Y))  (8-935)        qPi _(Cb)=ChromaQpTable[0][qPi _(Chroma)]  (8-936)        qPi _(Cr)=ChromaQpTable[1][qPi _(Chroma)]  (8-937)        qPi _(CbCr)=ChromaQpTable[2][qPi _(Chroma)]  (8-938)    -   The chroma quantization parameters for the Cb and Cr components,        Qp′_(Cb) and Qp′_(Cr), and joint Cb-Cr coding Qp′_(CbCr) are        derived as follows:        Qp′_(Cb)=Clip3(−QpBdOffset_(C),63,qP_(Cb)+pps_cb_qp_offset+slice_cb_qp_offset+CuQpOffset_(Cb))+QpBdOffset_(C)  (8-939)        Qp′_(Cr)=Clip3(−QpBdOffset_(C),63,qP_(Cr)+pps_cr_qp_offset+slice_cr_qp_offset+CuQpOffset_(Cr))+QpBdOffset_(C)  (8-940)        Qp′_(CbCr)=Clip3(−QpBdOffset_(C),63,qP_(CbCr)+pps_cbcr_qp_offset+slice_cbcr_qp_offset+CuQpOffset_(CbCr))+QpBdOffset_(C)  (8-941)        8.7.3 Scaling Process for Transform Coefficients        Inputs to this process are:    -   a luma location (xTbY, yTbY) specifying the top-left sample of        the current luma transform block relative to the top-left luma        sample of the current picture,    -   a variable nTbW specifying the transform blockwidth,    -   a variable nTbH specifying the transform block height,    -   a variable cIdx specifying the colour component of the current        block,    -   a variable bitDepth specifying the bit depth of the current        colour component.        Output of this process is the (nTbW)×(nTbH) array d of scaled        transform coefficients with elements d[x][y].        The quantization parameter qP is derived as follows:    -   If cIdx is equal to 0 and transform_skip_flag[xTbY][yTbY] is        equal to 0, the following applies:        qP=Qp′_(Y)  (8-950)    -   Otherwise, if cIdx is equal to 0 (and        transform_skip_flag[xTbY][yTbY] is equal to 1), the following        applies:        qP=Max(QpPrimeTsMin,Qp′_(Y))  (8-951)    -   Otherwise, if TuCResMode[xTbY][yTbY] is equal to 2, the        following applies:        qP=Qp′_(CbCr)  (8-952)    -   Otherwise, if cIdx is equal to 1, the following applies:        qP=Qp′_(Cb)  (8-953)    -   Otherwise (cIdx is equal to 2), the following applies:        qP=Qp′_(Cr)  (8-954)        2.7. Cross-Component Adaptive Loop Filter (CC-ALF)

FIG. 14A illustrates the placement of CC-ALF with respect to the otherloop filters. CC-ALF operates by applying a linear, diamond shapedfilter (FIG. 14B) to the luma channel for each chroma component, whichis expressed as

${{\Delta{I_{i}\left( {x,y} \right)}} = {\sum\limits_{{({x_{0},y_{0}})} \in S_{i}}{{I_{0}\left( {{x_{C} + x_{0}},{y_{C} + y_{0}}} \right)}{c_{i}\left( {x_{0},y_{0}} \right)}}}},$where

-   -   (x, y) is chroma component i location being refined    -   (x_(C), y_(C)) is the luma location based on (x, y)    -   S_(i) is filter support in luma for chroma component i    -   c_(i)(x₀, y₀) represents the filter coefficients

Key features characteristics of the CC-ALF process include:

-   -   The luma location (x_(C), y_(C)), around which the support        region is centered, is computed based on the spatial scaling        factor between the luma and chroma planes.    -   All filter coefficients are transmitted in the APS and have        8-bit dynamic range.    -   An APS may be referenced in the slice header.    -   CC-ALF coefficients used for each chroma component of a slice        are also stored in a buffer corresponding to a temporal        sublayer. Reuse of these sets of temporal sublayer filter        coefficients is facilitated using slice-level flags.    -   The application of the CC-ALF filters is controlled on a        variable block size and signalled by a context-coded flag        received for each block of samples. The block size along with an        CC-ALF enabling flag is received at the slice-level for each        chroma component.    -   Boundary padding for the horizontal virtual boundaries makes use        of repetition. For the remaining boundaries the same type of        padding is used as for regular ALF.

3. Drawbacks of Existing Implementations

DMVR and BIO do not involve the original signal during refining themotion vectors, which may result in coding blocks with inaccurate motioninformation. Also, DMVR and BIO sometimes employ the fractional motionvectors after the motion refinements while screen videos usually haveinteger motion vectors, which makes the current motion information moreinaccurate and make the coding performance worse.

-   -   1. The interaction between chroma QP table and chroma deblocking        may have problems, e.g. chroma QP table should be applied to        individual QP but not weighted sum of QPs.    -   2. The logic of luma deblocking filtering process is complicated        for hardware design.    -   3. The logic of boundary strength derivation is too complicated        for both software and hardware design.    -   4. In the BS decision process, JCCR is treated separately from        those blocks coded without JCCT applied. However, JCCR is only a        special way to code the residual. Therefore, such design may        bring additional complexity without no clear benefits.    -   5. In chroma edge decision, Qp_(Q) and Qp_(P) are set equal to        the Qp_(Y) values of the coding units which include the coding        blocks containing the sample q_(0,0) and p_(0,0), respectively.        However, in the quantization/de-quantization process, the QP for        a chroma sample is derived from the QP of luma block covering        the corresponding luma sample of the center position of current        chroma CU. When dual tree is enabled, the different locations of        luma blocks may result in different QPs. Therefore, in the        chroma deblocking process, wrong QPs may be used for filter        decision. Such a misalignment may result in visual artifacts. An        example is shown in FIGS. 9A-B. FIG. 9A shows the corresponding        CTB partitioning for luma block and FIG. 9B shows the chroma CTB        partitioning under dual tree. When determining the QP for chroma        block, denoted by CU_(c)1, the center position of CU_(c)1 is        firstly derived. Then the corresponding luma sample of the        center position of CU_(c)1 is identified and luma QP associated        with the luma CU that covers the corresponding luma sample,        i.e., CU_(Y)3 is then utilized to derive the QP for CU_(c)1.        However, when making filter decisions for the depicted three        samples (with solid circles), the QPs of CUs that cover the        corresponding 3 samples are selected. Therefore, for the 1^(st),        2^(nd), and 3^(rd) chroma sample (depicted in FIG. 9B), the QPs        of CU_(Y)2, CU_(Y)3, CU_(Y)4 are utilized, respectively. That        is, chroma samples in the same CU may use different QPs for        filter decision which may result in wrong decisions.    -   6. A different picture level QP offset (i.e.,        pps_joint_cbcr_qp_offset) is applied to JCCR coded blocks which        is different from the picture level offsets for Cb/Cr (e.g.,        pps_cb_qp_offset and pps_cr_qp_offset) applied to non-JCCR coded        blocks. However, in the chroma deblocking filter decision        process, only those offsets for non-JCCR coded blocks are        utilized. The missing of consideration of coded modes may result        in wrong filter decision.    -   7. The TS and non-TS coded blocks employ different QPs in the        de-quantization process, which may be also considered in the        deblocking process.    -   8. Different QPs are used in the scaling process        (quantization/dequantization) for JCCR coded blocks with        different modes. Such a design is not consistent.    -   9. The chroma deblocking for Cb/Cr could be unified for parallel        design.

4. Example Techniques and Embodiments

The detailed embodiments described below should be considered asexamples to explain general concepts. These embodiments should not beinterpreted narrowly way. Furthermore, these embodiments can be combinedin any manner.

The methods described below may be also applicable to other decodermotion information derivation technologies in addition to the DMVR andBIO mentioned below.

In the following examples, MVM[i].x and MVM[i].y denote the horizontaland vertical component of the motion vector in reference picture list i(i being 0 or 1) of the block at M (M being P or Q) side. Abs denotesthe operation to get the absolute value of an input, and “&&” and “∥”denotes the logical operation AND and OR. Referring to FIG. 10 , P maydenote the samples at P side and Q may denote the samples at Q side. Theblocks at P side and Q side may denote the block marked by the dashlines.

Regarding Chroma OP in Deblocking

-   -   1. When chroma QP table is used to derive parameters to control        chroma deblocking (e.g., in the decision process for chroma        block edges), chroma QP offsets may be applied after applying        chroma QP table.        -   a. In one example, the chroma QP offsets may be added to the            value outputted by a chroma QP table.        -   b. Alternatively, the chroma QP offsets may be not            considered as input to a chroma QP table.        -   c. In one example, the chroma QP offsets may be the            picture-level or other video unit-level            (slice/tile/brick/subpicture) chroma quantization parameter            offset (e.g., pps_cb_qp_offset, pps_cr_qp_offset in the            specification).    -   2. QP clipping may be not applied to the input of a chroma QP        table.    -   3. It is proposed that deblocking process for chroma components        may be based on the mapped chroma QP (by the chroma QP table) on        each side.        -   a. In one example, it is proposed that deblocking            parameters, (e.g., β and tC) for chroma may be based on QP            derived from luma QP on each side.        -   b. In one example, the chroma deblocking parameter may            depend on chroma QP table value with QpP as the table index,            where QpP, is the luma QP value on P-side.        -   c. In one example, the chroma deblocking parameter may            depend on chroma QP table value with QpQ as the table index,            where QpQ, is the luma QP value on Q-side.    -   4. It is proposed that deblocking process for chroma components        may be based on the QP applied to quantization/dequantization        for the chroma block.        -   a. In one example, QP for deblocking process may be equal to            the QP in dequantization.    -   5. It is proposed to consider the        picture/slice/tile/brick/subpicture level quantization parameter        offsets used for different coding methods in the deblocking        filter decision process.        -   a. In one example, selection of            picture/slice/tile/brick/subpicture level quantization            parameter offsets for filter decision (e.g., the chroma edge            decision in the deblocking filter process) may depend on the            coded methods for each side.        -   b. In one example, the filtering process (e.g., the chroma            edge decision process) which requires to use the            quantization parameters for chroma blocks may depend on            whether the blocks use JCCR.            -   i. Alternatively, furthermore, the picture/slice-level                QP offsets (e.g., pps_joint_cbcr_qp_offset) applied to                JCCR coded blocks may be further taken into                consideration in the deblocking filtering process.            -   ii. In one example, the cQpPicOffset which is used to                decide Tc and β settings may be set to                pps_joint_cbcr_qp_offset instead of pps_cb_qp_offset or                pps_cr_qp_offset under certain conditions:                -   1. In one example, when either block in P or Q sides                    uses JCCR.                -   2. In one example, when both blocks in P or Q sides                    uses JCCR.            -   iii. Alternatively, furthermore, the filtering process                may depend on the mode of JCCR (e.g., whether mode is                equal to 2).    -   6. The chroma filtering process (e.g., the chroma edge decision        process) which requires to access the decoded information of a        luma block may utilize the information associated with the same        luma coding block that is used to derive the chroma QP in the        dequantization/quantization process.        -   a. In one example, the chroma filtering process (e.g., the            chroma edge decision process) which requires to use the            quantization parameters for luma blocks may utilize the luma            coding unit covering the corresponding luma sample of the            center position of current chroma CU.        -   b. An example is depicted in FIGS. 9A-B wherein the decoded            information of CU_(Y)3 may be used for filtering decision of            the three chroma samples (1^(st), 2^(nd) and 3^(rd)) in FIG.            9B.    -   7. The chroma filtering process (e.g., the chroma edge decision        process) may depend on the quantization parameter applied to the        scaling process of the chroma block (e.g.,        quantization/dequantization).        -   a. In one example, the QP used to derive β and Tc may depend            on the QP applied to the scaling process of the chroma            block.        -   b. Alternatively, furthermore, the QP used to the scaling            process of the chroma block may have taken the chroma CU            level QP offset into consideration.    -   8. Whether to invoke above bullets may depend on the sample to        be filtered is in the block at P or Q side.        -   a. For example, whether to use the information of the luma            coding block covering the corresponding luma sample of            current chroma sample or use the information of the luma            coding block covering the corresponding luma sample of            center position of chroma coding block covering current            chroma sample may depend on the block position.            -   i. In one example, if the current chroma sample is in                the block at the Q side, QP information of the luma                coding block covering the corresponding luma sample of                center position of chroma coding block covering current                chroma sample may be used.            -   ii. In one example, if the current chroma sample is in                the block at the P side, QP information of the luma                coding block covering the corresponding luma sample of                the chroma sample may be used.    -   9. Chroma QP used in deblocking may depend on information of the        corresponding transform block.        -   a. In one example, chroma QP for deblocking at P-side may            depend on the transform block's mode at P-side.            -   i. In one example, chroma QP for deblocking at P-side                may depend on if the transform block at P-side is coded                with JCCR applied.            -   ii. In one example, chroma QP for deblocking at P-side                may depend on if the transform block at P-side is coded                with joint_cb_cr mode and the mode of JCCR is equal to                2.        -   b. In one example, chroma QP for deblocking at Q-side may            depend on the transform block's mode at Q-side.            -   i. In one example, chroma QP for deblocking at Q-side                may depend on if the transform block at Q-side is coded                with JCCR applied.            -   ii. In one example, chroma QP for deblocking at Q-side                may depend on if the transform block at Q-side is coded                with JCCR applied and the mode of JCCR is equal to 2.    -   10. Signaling of chroma QPs may be in coding unit.        -   a. In one example, when coding unit size is larger than the            maximum transform block size, i.e., maxTB, chroma QP may be            signaled in CU level. Alternatively, it may be signaled in            TU level.        -   b. In one example, when coding unit size is larger than the            size of VPDU, chroma QP may be signaled in CU level.            Alternatively, it may be signaled in TU level.    -   11. Whether a block is of joint_cb_cr mode may be indicated at        coding unit level.        -   a. In one example, whether a transform block is of            joint_cb_cr mode may inherit the information of the coding            unit containing the transform block.    -   12. Chroma QP used in deblocking may depend on chroma QP used in        scaling process minus QP offset due to bit depth.        -   a. In one example, Chroma QP used in deblocking at P-side is            set to the JCCR chroma QP used in scaling process, i.e.            Qp′_(CbCr), minus QpBdOffsetC when TuCResMode[xTb][yTb] is            equal to 2 where (xTb, yTb) denotes the transform blocking            containing the first sample at P-side, i.e. p_(0,0).        -   b. In one example, Chroma QP used in deblocking at P-side is            set to the Cb chroma QP used in scaling process, i.e.            Qp′_(Cb), minus QpBdOffsetC when TuCResMode[xTb][yTb] is            equal to 2 where (xTb, yTb) denotes the transform blocking            containing the first sample at P-side, i.e. p_(0,0).        -   c. In one example, Chroma QP used in deblocking at P-side is            set to the Cr chroma QP used in scaling process, i.e.            Qp′_(Cr), minus QpBdOffsetC when TuCResMode[xTb][yTb] is            equal to 2 where (xTb, yTb) denotes the transform blocking            containing the first sample at P-side, i.e. p_(0,0).        -   d. In one example, Chroma QP used in deblocking at Q-side is            set to the JCCR chroma QP used in scaling process, i.e.            Qp′_(CbCr), minus QpBdOffsetC when TuCResMode[xTb][yTb] is            equal to 2 where (xTb, yTb) denotes the transform blocking            containing the last sample at Q-side, i.e. q_(0,0).        -   e. In one example, Chroma QP used in deblocking at Q-side is            set to the Cb chroma QP used in scaling process, i.e.            Qp′_(Cb), minus QpBdOffsetC when TuCResMode[xTb][yTb] is            equal to 2 where (xTb, yTb) denotes the transform blocking            containing the last sample at Q-side, i.e. q_(0,0).    -   13. In one example, Chroma QP used in deblocking at Q-side is        set to the Cr chroma QP used in scaling process, i.e. Qp′_(Cr),        minus QpBdOffsetC when TuCResMode[xTb][yTb] is equal to 2 where        (xTb, yTb) denotes the transform blocking containing the last        sample at Q-side, i.e. q_(0,0).        Regarding OP Settings    -   14. It is proposed to signal the indication of enabling        block-level chroma QP offset (e.g.        slice_cu_chroma_qp_offset_enabled_flag) at the        slice/tile/brick/subpicture level.        -   a. Alternatively, the signaling of such an indication may be            conditionally signaled.            -   i. In one example, it may be signaled under the                condition of JCCR enabling flag.            -   ii. In one example, it may be signaled under the                condition of block-level chroma QP offset enabling flag                in picture level.            -   iii. Alternatively, such an indication may be derived                instead.        -   b. In one example, the            slice_cu_chroma_qp_offset_enabled_flag may be signaled only            when the PPS flag of chroma QP offset (e.g.            slice_cu_chroma_qp_offset_enabled_flag) is true.        -   c. In one example, the            slice_cu_chroma_qp_offset_enabled_flag may be inferred to            false only when the PPS flag of chroma QP offset (e.g.            slice_cu_chroma_qp_offset_enabled_flag) is false.        -   d. In one example, whether to use the chroma QP offset on a            block may be based on the flags of chroma QP offset at PPS            level and/or slice level.    -   15. Same QP derivation method is used in the scaling process        (quantization/dequantization) for JCCR coded blocks with        different modes.        -   a. In one example, for JCCR with mode 1 and 3, the QP is            dependent on the QP offset signaled in the picture/slice            level (e.g., pps_cbcr_qp_offset, slice_cbcr_qp_offset).            Filtering Procedures    -   16. Deblocking for all color components excepts for the first        color component may follow the deblocking process for the first        color component.        -   a. In one example, when the color format is 4:4:4,            deblocking process for the second and third components may            follow the deblocking process for the first component.        -   b. In one example, when the color format is 4:4:4 in RGB            color space, deblocking process for the second and third            components may follow the deblocking process for the first            component.        -   c. In one example, when the color format is 4:2:2, vertical            deblocking process for the second and third components may            follow the vertical deblocking process for the first            component.        -   d. In above examples, the deblocking process may refer to            deblocking decision process and/or deblocking filtering            process.    -   17. How to calculate gradient used in the deblocking filter        process may depend on the coded mode information and/or        quantization parameters.        -   a. In one example, the gradient computation may only            consider the gradient of a side wherein the samples at that            side are not lossless coded.        -   b. In one example, if both sides are lossless coded or            nearly lossless coded (e.g., quantization parameters equal            to 4), gradient may be directly set to 0.            -   i. Alternatively, if both sides are lossless coded or                nearly lossless coded (e.g., quantization parameters                equal to 4), Boundary Strength (e.g., BS) may be set to                0.        -   c. In one example, if the samples at P side are lossless            coded and the samples at Q side are lossy coded, the            gradients used in deblocking on/off decision and/or strong            filters on/off decision may only include gradients of the            samples at Q side, vice versa.            -   i. Alternatively, furthermore, the gradient of one side                may be scaled by N.                -   1. N is an integer number (e.g. 2) and may depend on                -    a. Video contents (e.g. screen contents or natural                    contents)                -    b. A message signaled in the                    DPS/SPS/VPS/PPS/APS/picture header/slice header/tile                    group header/Largest coding unit (LCU)/Coding unit                    (CU)/LCU row/group of LCUs/TU/PU block/Video coding                    unit                -    c. Position of CU/PU/TU/block/Video coding unit                -    d. Coded modes of blocks containing the samples                    along the edges                -    e. Transform matrices applied to the blocks                    containing the samples along the edges                -    f. Block dimension/Block shape of current block                    and/or its neighboring blocks                -    g. Indication of the color format (such as 4:2:0,                    4:4:4, RGB or YUV)                -    h. Coding tree structure (such as dual tree or                    single tree)                -    i. Slice/tile group type and/or picture type                -    j. Color component (e.g. may be only applied on Cb                    or Cr)                -    k. Temporal layer ID                -    l. Profiles/Levels/Tiers of a standard                -    m. Alternatively, N may be signalled to the decoder                    Regarding Boundary Strength Derivation    -   18. It is proposed to treat JCCR coded blocks as those non-JCCR        coded blocks in the boundary strength decision process.        -   a. In one example, the determination of boundary strength            (BS) may be independent from the checking of usage of JCCR            for two blocks at P and Q sides.        -   b. In one example, the boundary strength (BS) for a block            may be determined regardless if the block is coded with JCCR            or not.    -   19. It is proposed to derive the boundary strength (BS) without        comparing the reference pictures and/or number of MVs associated        with the block at P side with the reference pictures of the        block at Q side.        -   a. In one example, deblocking filter may be disabled even            when two blocks are with different reference pictures.        -   b. In one example, deblocking filter may be disabled even            when two blocks are with different number of MVs (e.g., one            is uni-predicted and the other is bi-predicted).        -   c. In one example, the value of BS may be set to 1 when            motion vector differences for one or all reference picture            lists between the blocks at P side and Q side is larger than            or equal to a threshold Th.            -   i. Alternatively, furthermore, the value of BS may be                set to 0 when motion vector differences for one or all                reference picture lists between the blocks at P side and                Q side is smaller than or equal to a threshold Th.        -   d. In one example, the difference of the motion vectors of            two blocks being larger than a threshold Th may be defined            as            (Abs(MVP[0].x−MVQ[0].x)>Th∥Abs(MVP[0].y−MVQ[0].y)>Th∥Abs(MVP[1].x−MVQ[1].x)>Th)∥Abs(MVP[1].y−MVQ[1].y)>Th)            -   ii. Alternatively, the difference of the motion vectors                of two blocks being larger than a threshold Th may be                defined as (Abs(MVP[0].x−MVQ[0].x)>Th &&                Abs(MVP[0].y−MVQ[0].y)>Th && Abs(MVP[1].x−MVQ[1].x)>Th)                && Abs(MVP[1].y−MVQ[1].y)>Th)            -   iii. Alternatively, in one example, the difference of                the motion vectors of two blocks being larger than a                threshold Th may be defined as                (Abs(MVP[0].x−MVQ[0].x)>Th∥Abs(MVP[0].y−MVQ[0].y)>Th) &&                (Abs(MVP[1].x−MVQ[1].x)>Th)∥Abs(MVP[1].y−MVQ[1].y)>Th)            -   iv. Alternatively, in one example, the difference of the                motion vectors of two blocks being larger than a                threshold Th may be defined as                (Abs(MVP[0].x−MVQ[0].x)>Th &&                Abs(MVP[0].y−MVQ[0].y)>Th∥(Abs(MVP[1].x−MVQ[1].x)>Th) &&                Abs(MVP[1].y−MVQ[1].y)>Th)        -   e. In one example, a block which does not have a motion            vector in a given list may be treated as having a            zero-motion vector in that list.        -   f. In the above examples, Th is an integer number (e.g. 4, 8            or 16).        -   g. In the above examples, Th may depend on            -   v. Video contents (e.g. screen contents or natural                contents)            -   vi. A message signaled in the                DPS/SPS/VPS/PPS/APS/picture header/slice header/tile                group header/Largest coding unit (LCU)/Coding unit                (CU)/LCU row/group of LCUs/TU/PU block/Video coding unit            -   vii. Position of CU/PU/TU/block/Video coding unit            -   viii. Coded modes of blocks containing the samples along                the edges            -   ix. Transform matrices applied to the blocks containing                the samples along the edges            -   x. Block dimension/Block shape of current block and/or                its neighboring blocks            -   xi. Indication of the color format (such as 4:2:0,                4:4:4, RGB or YUV)            -   xii. Coding tree structure (such as dual tree or single                tree)            -   xiii. Slice/tile group type and/or picture type            -   xiv. Color component (e.g. may be only applied on Cb or                Cr)            -   xv. Temporal layer ID            -   xvi. Profiles/Levels/Tiers of a standard            -   xvii. Alternatively, Th may be signalled to the decoder.        -   h. The above examples may be applied under certain            conditions.            -   xviii. In one example, the condition is the blkP and                blkQ are not coded with intra modes.            -   xix. In one example, the condition is the blkP and blkQ                have zero coefficients on luma component.            -   xx. In one example, the condition is the blkP and blkQ                are not coded with the CIIP mode.            -   xxi. In one example, the condition is the blkP and blkQ                are coded with a same prediction mode (e.g. IBC or                Inter).                Regarding Luma Deblocking Filtering Process    -   20. The deblocking may use different QPs for TS coded blocks and        non-TS coded blocks.        -   a. In one example, the QP for TS may be used on TS coded            blocks while the QP for non-TS may be used on non-TS coded            blocks.    -   21. The luma filtering process (e.g., the luma edge decision        process) may depend on the quantization parameter applied to the        scaling process of the luma block.        -   a. In one example, the QP used to derive beta and Tc may            depend on the clipping range of transform skip, e.g. as            indicated by QpPrimeTsMin.    -   22. It is proposed to use an identical gradient computation for        large block boundaries and smaller block boundaries.        -   a. In one example, the deblocking filter on/off decision            described in section 2.1.4 may be also applied for large            block boundary.            -   i. In one example, the threshold beta in the decision                may be modified for large block boundary.                -   1. In one example, beta may depend on quantization                    parameter.                -   2. In one example, beta used for deblocking filter                    on/off decision for large block boundaries may be                    smaller than that for smaller block boundaries.                -    a. Alternatively, in one example, beta used for                    deblocking filter on/off decision for large block                    boundaries may be larger than that for smaller block                    boundaries.                -    b. Alternatively, in one example, beta used for                    deblocking filter on/off decision for large block                    boundaries may be equal to that for smaller block                    boundaries.            -   3. In one example, beta is an integer number and may be                based on                -    a. Video contents (e.g. screen contents or natural                    contents)                -    b. A message signaled in the                    DPS/SPS/VPS/PPS/APS/picture header/slice header/tile                    group header/Largest coding unit (LCU)/Coding unit                    (CU)/LCU row/group of LCUs/TU/PU block/Video coding                    unit                -    c. Position of CU/PU/TU/block/Video coding unit                -    d. Coded modes of blocks containing the samples                    along the edges                -    e. Transform matrices applied to the blocks                    containing the samples along the edges                -    f. Block dimension of current block and/or its                    neighboring blocks                -    g. Block shape of current block and/or its                    neighboring blocks                -    h. Indication of the color format (such as 4:2:0,                    4:4:4, RGB or YUV)                -    i. Coding tree structure (such as dual tree or                    single tree)                -    j. Slice/tile group type and/or picture type                -    k. Color component (e.g. may be only applied on Cb                    or Cr)                -    l. Temporal layer ID                -    m. Profiles/Levels/Tiers of a standard                -    n. Alternatively, beta may be signalled to the                    decoder.                    Regarding Scaling Matrix (Dequantization Matrix)    -   23. The values for specific positions of quantization matrices        may be set to constant.        -   a. In one example, the position may be the position of            (x, y) wherein x and y are two integer variables (e.g.,            x=y=0), and (x, y) is the coordinate relative to a            TU/TB/PU/PB/CU/CB.            -   i. In one example, the position may be the position of                DC.        -   b. In one example, the constant value may be 16.        -   c. In one example, for those positions, signaling of the            matrix values may not be utilized.    -   24. A constrain may be set that the average/weighted average of        some positions of quantization matrices may be a constant.        -   a. In one example, deblocking process may depend on the            constant value.        -   b. In one example, the constant value may be indicated in            DPS/VPS/SPS/PPS/Slice/Picture/Tile/Brick headers.    -   25. One or multiple indications may be signaled in the picture        header to inform the scaling matrix to be selected in the        picture associated with the picture header.        Regarding Cross Component Adaptive Loop Filter (CCALF)    -   26. CCALF may be applied before some loop filtering process at        the decoder        -   a. In one example, CCALF may be applied before deblocking            process at the decoder.        -   b. In one example, CCALF may be applied before SAO at the            decoder.        -   c. In one example, CCALF may be applied before ALF at the            decoder.        -   d. Alternatively, the order of different filters (e.g.,            CCALF, ALF, SAO, deblocking filter) may be NOT fixed.            -   i. In one example, the invoke of CCLAF may be before one                filtering process for one video unit or after another                one for another video unit.            -   ii. In one example, the video unit may be a                CTU/CTB/slice/tile/brick/picture/sequence.        -   e. Alternatively, indications of the order of different            filters (e.g., CCALF, ALF, SAO, deblocking filter) may be            signaled or derived on-the-fly.            -   i. Alternatively, indication of the invoking of CCALF                may be signaled or derived on-the-fly.        -   f. The explicit (e.g. signaling from the encoder to the            decoder) or implicit (e.g. derived at both encoder and            decoder) indications of how to control CCALF may be            decoupled for different color components (such as Cb and            Cr).        -   g. Whether and/or how to apply CCALF may depend on color            formats (such as RGB and YCbCr) and/or color sampling format            (such as 4:2:0, 4:2:2 and 4:4:4), and/or color down-sampling            positions or phases)            Regarding Chroma OP Offset Lists    -   27. Signaling and/or selection of chroma QP offset lists may be        dependent on the coded prediction modes/picture types/slice or        tile or brick types.        -   h. Chroma QP offset lists, e.g. cb_qp_offset_list[i],            cr_qp_offset_list[i], and joint_cbcr_qp_offset_list[i], may            be different for different coding modes.        -   i. In one example, whether and how to apply chroma QP offset            lists may depend on whether the current block is coded in            intra mode.        -   j. In one example, whether and how to apply chroma QP offset            lists may depend on whether the current block is coded in            inter mode.        -   k. In one example, whether and how to apply chroma QP offset            lists may depend on whether the current block is coded in            palette mode.        -   l. In one example, whether and how to apply chroma QP offset            lists may depend on whether the current block is coded in            IBC mode.        -   m. In one example, whether and how to apply chroma QP offset            lists may depend on whether the current block is coded in            transform skip mode.        -   n. In one example, whether and how to apply chroma QP offset            lists may depend on whether the current block is coded in            BDPCM mode.        -   o. In one example, whether and how to apply chroma QP offset            lists may depend on whether the current block is coded in            transform_quant_skip or lossless mode.            Regarding Chroma Deblocking at CTU Boundary    -   28. How to select the QPs (e.g., using corresponding luma or        chroma dequantized QP) utilized in the deblocking filter process        may be dependent on the position of samples relative to the        CTU/CTB/VPDU boundaries.    -   29. How to select the QPs (e.g., using corresponding luma or        chroma dequantized QP) utilized in the deblocking filter process        may depend on color formats (such as RGB and YCbCr) and/or color        sampling format (such as 4:2:0, 4:2:2 and 4:4:4), and/or color        down-sampling positions or phases).    -   30. For edges at CTU boundary, the deblocking may be based on        luma QP of the corresponding blocks.        -   p. In one example, for horizontal edges at CTU boundary, the            deblocking may be based on luma QP of the corresponding            blocks.            -   i. In one example, the deblocking may be based on luma                QP of the corresponding blocks at P-side.            -   ii. In one example, the deblocking may be based on luma                QP of the corresponding blocks at Q-side.        -   q. In one example, for vertical edges at CTU boundary, the            deblocking may be based on luma QP of the corresponding            blocks.            -   i. In one example, the deblocking may be based on luma                QP of the corresponding blocks at P-side.            -   ii. In one example, the deblocking may be based on luma                QP of the corresponding blocks at Q-side.        -   r. In one example, for edges at CTU boundary, the deblocking            may be based on luma QP at P-side and chroma QP at Q-side.        -   s. In one example, for edges at CTU boundary, the deblocking            may be based on luma QP at Q-side and chroma QP at P-side.        -   t. In this bullet, “CTU boundary” may refer to a specific            CTU boundary such as the upper CTU boundary or the lower CTU            boundary.    -   31. For horizontal edges at CTU boundary, the deblocking may be        based on a function of chroma QPs at P-side.        -   u. In one example, the deblocking may be based on an            averaging function of chroma QPs at P-side.            -   i. In one example, the function may be based on the                average of the chroma QPs for each 8 luma samples.            -   ii. In one example, the function may be based on the                average of the chroma QPs for each 16 luma samples.            -   iii. In one example, the function may be based on the                average of the chroma QPs for each 32 luma samples.            -   iv. In one example, the function may be based on the                average of the chroma QPs for each 64 luma samples.            -   v. In one example, the function may be based on the                average of the chroma QPs for each CTU.            -   v. In one example, the deblocking may be based on a                maximum function of chroma QPs at P-side.                -   i. In one example, the function may be based on the                    maximum of the chroma QPs for each 8 luma samples.                -   ii. In one example, the function may be based on the                    maximum of the chroma QPs for each 16 luma samples.                -   iii. In one example, the function may be based on                    the maximum of the chroma QPs for each 32 luma                    samples.                -   iv. In one example, the function may be based on the                    maximum of the chroma QPs for each 64 luma samples.                -   v. In one example, the function may be based on the                    maximum of the chroma QPs for each CTU.        -   w. In one example, the deblocking may be based on a minimum            function of chroma QPs at P-side.            -   i. In one example, the function may be based on the                minimum of the chroma QPs for each 8 luma samples.            -   ii. In one example, the function may be based on the                minimum of the chroma QPs for each 16 luma samples.            -   iii. In one example, the function may be based on the                minimum of the chroma QPs for each 32 luma samples.            -   iv. In one example, the function may be based on the                minimum of the chroma QPs for each 64 luma samples.            -   v. In one example, the function may be based on the                minimum of the chroma QPs for each CTU.        -   x. In one example, the deblocking may be based on a            subsampling function of chroma QPs at P-side.            -   i. In one example, the function may be based on the                chroma QPs of the k-th chroma sample for each 8 luma                samples.                -   1. In one example, the k-th sample may be the first                    sample.                -   2. In one example, the k-th sample may be the last                    sample.                -   3. In one example, the k-th sample may be the third                    sample.                -   4. In one example, the k-th sample may be the fourth                    sample.            -   ii. In one example, the function may be based on the                chroma QPs of the k-th chroma sample for each 16 luma                samples.                -   1. In one example, the k-th sample may be the first                    sample.                -   2. In one example, the k-th sample may be the last                    sample.                -   3. In one example, the k-th sample may be the 7-th                    sample.                -   4. In one example, the k-th sample may be the 8-th                    sample.            -   iii. In one example, the function may be based on the                chroma QPs of the k-th chroma sample for each 32 luma                samples.                -   1. In one example, the k-th sample may be the first                    sample.                -   2. In one example, the k-th sample may be the last                    sample.                -   3. In one example, the k-th sample may be the 15-th                    sample.                -   4. In one example, the k-th sample may be the 16-th                    sample.            -   iv. In one example, the function may be based on the                chroma QPs of the k-th chroma sample for each 64 luma                samples.                -   1. In one example, the k-th sample may be the first                    sample.                -   2. In one example, the k-th sample may be the last                    sample.                -   3. In one example, the k-th sample may be the 31-th                    sample.                -   4. In one example, the k-th sample may be the 32-th                    sample.            -   v. In one example, the function may be based on the                chroma QPs of the k-th chroma sample for each CTU.        -   y. Alternatively, the above items may be applied to chroma            QPs at Q-side for deblocking process.    -   32. It may be constrained that QP for chroma component may be        the same for a chroma row segment with length 4*m starting from        (4*m*x, 2y) relative to top-left of the picture, where x and y        are non-negative integers; and m is a positive integer.        -   z. In one example, m may be equal to 1.        -   aa. In one example, the width of a quantization group for            chroma component must be no smaller than 4*m.    -   33. It may be constrained that QP for chroma component may be        the same for a chroma column segment with length 4*n starting        from (2*x, 4*n*y) relative to top-left of the picture, where x        and y are non-negative integers; and n is a positive integer.        -   bb. In one example, n may be equal to 1.        -   cc. In one example, the height of a quantization group for            chroma component must be no smaller than 4*n.            Regarding Chroma Deblocking Filtering Process    -   34. A first syntax element controlling the usage of coding tool        X may be signalled in a first video unit (such as picture        header), depending on a second syntax element signalled in a        second video unit (such as SPS or PPS, or VPS).        -   a. In one example, the first syntax element is signalled            only if the second syntax element indicates that the coding            tool X is enabled.        -   b. In one example, X is Bi-Direction Optical Flow (BDOF).        -   c. In one example, X is Prediction Refinement Optical Flow            (PROF).        -   d. In one example, X is Decoder-side Motion Vector            Refinement (DMVR).        -   e. In one example, the signalling of the usage of a coding            tool X may be under the condition check of slice types            (e.g., P or B slices; non-I slices).            Regarding Chroma Deblocking Filtering Process    -   35. Deblocking filter decision processes for two chroma blocks        may be unified to be only invoked once and the decision is        applied to two chroma blocks.        -   b. In one example, the decision for whether to perform            deblocking filter may be same for Cb and Cr components.        -   c. In one example, if the deblocking filter is determined to            be applied, the decision for whether to perform stronger            deblocking filter may be same for Cb and Cr components.        -   d. In one example, the deblocking condition and strong            filter on/off condition, as described in section 2.2.7, may            be only checked once. However, it may be modified to check            the information of both chroma components.            -   i. In one example, the average of gradients of Cb and Cr                components may be used in the above decisions for both                Cb and Cr components.            -   ii. In one example, the chroma stronger filters may be                performed only when the strong filter condition is                satisfied for both Cb and Cr components.                -   1. Alternatively, in one example, the chroma weak                    filters may be performed only when the strong filter                    condition is not satisfied at least one chroma                    component                    General    -   36. The above proposed methods may be applied under certain        conditions.        -   a. In one example, the condition is the colour format is            4:2:0 and/or 4:2:2.            -   i. Alternatively, furthermore, for 4:4:4 colour format,                how to apply deblocking filter to the two colour chroma                components may follow the current design.        -   b. In one example, indication of usage of the above methods            may be signalled in sequence/picture/slice/tile/brick/a            video region-level, such as SPS/PPS/picture header/slice            header.        -   c. In one example, the usage of above methods may depend on            -   ii. Video contents (e.g. screen contents or natural                contents)            -   iii. A message signaled in the                DPS/SPS/VPS/PPS/APS/picture header/slice header/tile                group header/Largest coding unit (LCU)/Coding unit                (CU)/LCU row/group of LCUs/TU/PU block/Video coding unit            -   iv. Position of CU/PU/TU/block/Video coding unit                -   a. In one example, for filtering samples along the                    CTU/CTB boundaries (e.g., the first K (e.g., K=4/8)                    to the top/left/right/bottom boundaries), the                    existing design may be applied. While for other                    samples, the proposed method (e.g., bullets 3/4) may                    be applied instead.            -   v. Coded modes of blocks containing the samples along                the edges            -   vi. Transform matrices applied to the blocks containing                the samples along the edges            -   vii. Block dimension of current block and/or its                neighboring blocks            -   viii. Block shape of current block and/or its                neighboring blocks            -   ix. Indication of the color format (such as 4:2:0,                4:4:4, RGB or YUV)            -   x. Coding tree structure (such as dual tree or single                tree)            -   xi. Slice/tile group type and/or picture type            -   xii. Color component (e.g. may be only applied on Cb or                Cr)            -   xiii. Temporal layer ID            -   xiv. Profiles/Levels/Tiers of a standard            -   xv. Alternatively, m and/or n may be signalled to the                decoder.

5. Additional Embodiments

The newly added texts are shown in underlined bold italicized font. Thedeleted texts are marked by [[ ]].

5.1. Embodiment #1 on Chroma QP in Deblocking

8.8.3.6 Edge Filtering Process for One Direction

. . .

-   -   Otherwise (cIdx is not equal to 0), the filtering process for        edges in the chroma coding block of current coding unit        specified by cIdx consists of the following ordered steps:        -   1. The variable cQpPicOffset is derived as follows:            cQpPicOffset=cIdx==1?pps_cb_qp_offset:pps_cr_qp_offset  (8-1065)            8.8.3.6.3 Decision Process for Chroma Block Edges            . . .            The variables Qp_(Q) and Qp_(P) are set equal to the Qp_(Y)            values of the coding units which include the coding blocks            containing the sample q_(0,0) and p_(0,0), respectively.            The variable Qp_(C) is derived as follows:            [[qPi=Clip3(0,63,((Qp_(Q)+Qp_(P)+1)>>1)+cQpPicOffset)  (8-1132)            Qp_(C)=ChromaQpTable[cIdx−1][qPi]  (8-1133)]]            qPi=(Qp_(Q)+Qp_(P)+1)>>1  (8-1132)            Qp_(C)=ChomaQpTable[cIdx−1][qPi]+cQpPicOffset  (8-1133)    -   NOTE—The variable cQpPicOffset provides an adjustment for the        value of pps_cb_qp_offset or pps_cr_qp_offset, according to        whether the filtered chroma component is the Cb or Cr component.        However, to avoid the need to vary the amount of the adjustment        within the picture, the filtering process does not include an        adjustment for the value of slice_cb_qp_offset or        slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is        equal to 1) for the value of CuQpOffset_(Cb), CuQpOffset_(Cr),        or CuQpOffset_(CbCr).        The value of the variable β′ is determined as specified in Table        8-18 based on the quantization parameter Q derived as follows:        Q=Clip3(0,63,Qp_(C)+(slice_beta_offset_div2<<1))  (8-1134)        where slice_beta_offset_div2 is the value of the syntax element        slice_beta_offset_div2 for the slice that contains sample        q_(0,0).        The variable β is derived as follows:        β=β′*(1<<(BitDepth_(C)−8))  (8-1135)        The value of the variable t_(C)′ is determined as specified in        Table 8-18 based on the chroma quantization parameter Q derived        as follows:        Q=Clip3(0,65,Qp_(C)+2*(bS−1)+(slice_tc_offset_div2<<1))  (8-1136)        where slice_tc_offset_div2 is the value of the syntax element        slice_tc_offset_div2 for the slice that contains sample q_(0,0).        The variable t_(C) is derived as follows:        t _(C)=(BitDepth_(C)<10)?(t _(C)′+2)>>(10−BitDepth_(C)):t        _(C)′*(1<<(BitDepth_(C)−8))   (8-1137)

5.2. Embodiment #2 on Boundary Strength Derivation

8.8.3.5 Derivation Process of Boundary Filtering Strength

Inputs to this process are:

-   -   a picture sample array recPicture,    -   a location (xCb, yCb) specifying the top-left sample of the        current coding block relative to the top-left sample of the        current picture,    -   a variable nCbW specifying the width of the current coding        block,    -   a variable nCbH specifying the height of the current coding        block,    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered,    -   a variable cIdx specifying the colour component of the current        coding block,    -   a two-dimensional (nCbW)×(nCbH) array edgeFlags.        Output of this process is a two-dimensional (nCbW)×(nCbH) array        b S specifying the boundary filtering strength.        . . .        For xD_(i) with i=0 . . . xN and yD_(j) with j=0 . . . yN, the        following applies:    -   If edgeFlags[xD_(i)][yD_(j)] is equal to 0, the variable        bS[xD_(i)][yD_(j)] is set equal to 0.    -   Otherwise, the following applies:        -   . . .        -   The variable bS[xD_(i)][yD_(j)] is derived as follows:            -   If cIdx is equal to 0 and both samples p₀ and q₀ are in                a coding block with intra_bdpcm_flag equal to 1,                bS[xD_(i)][yD_(j)] is set equal to 0.            -   Otherwise, if the sample p₀ or q₀ is in the coding block                of a coding unit coded with intra prediction mode,                bS[xD_(i)][yD_(j)] is set equal to 2.            -   Otherwise, if the block edge is also a transform block                edge and the sample p₀ or q₀ is in a coding block with                ciip_flag equal to 1, bS[xD_(i)][yD_(j)] is set equal to                2.            -   Otherwise, if the block edge is also a transform block                edge and the sample p₀ or q₀ is in a transform block                which contains one or more non-zero transform                coefficient levels, bS[xD_(i)][yD_(j)] is set equal to                1.            -   Otherwise, if the block edge is also a transform block                edge, cIdx is greater than 0, and the sample p₀ or q₀ is                in a transform unit with tu_joint_cbcr_residual_flag                equal to 1, bS[xD_(i)][yD_(j)] is set equal to 1.            -   Otherwise, if the prediction mode of the coding subblock                containing the sample p₀ is different from the                prediction mode of the coding subblock containing the                sample q₀ (i.e. one of the coding subblock is coded in                IBC prediction mode and the other is coded in inter                prediction mode), bS[xD_(i)][yD_(j)] is set equal to 1            -   Otherwise, if cIdx is equal to 0 and one or more of the                following conditions are true, bS[xD_(i)][yD_(j)] is set                equal to 1:                -   

                -   [[The coding subblock containing the sample p₀ and                    the coding subblock containing the sample q₀ are                    both coded in IBC prediction mode, and the absolute                    difference between the horizontal or vertical                    component of the block vectors used in the                    prediction of the two coding subblocks is greater                    than or equal to 8 in units of 1/16 luma samples.

                -   For the prediction of the coding subblock containing                    the sample p₀ different reference pictures or a                    different number of motion vectors are used than for                    the prediction of the coding subblock containing the                    sample q₀.

                -    NOTE 1—The determination of whether the reference                    pictures used for the two coding subblocks are the                    same or different is based only on which pictures                    are referenced, without regard to whether a                    prediction is formed using an index into reference                    picture list 0 or an index into reference picture                    list 1, and also without regard to whether the index                    position within a reference picture list is                    different.

                -    NOTE 2—The number of motion vectors that are used                    for the prediction of a coding subblock with                    top-left sample covering (xSb, ySb), is equal to                    PredFlagL0[xSb][ySb]+PredFlagL1[xSb][ySb].

                -   One motion vector is used to predict the coding                    subblock containing the sample p₀ and one motion                    vector is used to predict the coding subblock                    containing the sample q₀, and the absolute                    differencebetweenthehorizontalorverticalcomponentofthemotionvectorsusedis                    greater than or equal to 8 in units of 1/16 luma                    samples.

                -   Two motion vectors and two different reference                    pictures are used to predict the coding subblock                    containing the sample p₀, two motion vectors for the                    same two reference pictures are used to predict the                    coding subblock containing the sample q₀ and the                    absolute difference between the horizontal or                    vertical component of the two motion vectors used in                    the prediction of the two coding subblocks for the                    same reference picture is greater than or equal to 8                    in units of 1/16 luma samples.

                -   Two motion vectors for the same reference picture                    are used to predict the coding subblock containing                    the sample p₀, two motion vectors for the same                    reference picture are used to predict the coding                    subblock containing the sample q₀ and both of the                    following conditions are true:

                -    The absolute difference between the horizontal or                    vertical component of list 0 motion vectors used in                    the prediction of the two coding subblocks is                    greater than or equal to 8 in 1/16 luma samples, or                    the absolute difference between the horizontal or                    vertical component of the list 1 motion vectors used                    in the prediction of the two coding subblocks is                    greater than or equal to 8 in units of 1/16 luma                    samples.

                -   The absolute difference between the horizontal or                    vertical component of list 0 motion vector used in                    the prediction of the coding subblock containing the                    sample p₀ and the list 1 motion vector used in the                    prediction of the coding subblock containing the                    sample q₀ is greater than or equal to 8 in units of                    1/16 luma samples, or the absolute difference                    between the horizontal or vertical component of the                    list 1 motion vector used in the prediction of the                    coding subblock containing the sample p₀ and list 0                    motion vector used in the prediction of the coding                    subblock containing the sample q₀ is greater than or                    equal to 8 in units of 1/16 luma samples.]]            -   Otherwise, the variable bS[xD_(i)][yD_(j)] is set equal                to 0.

5.3. Embodiment #3 on Boundary Strength Derivation

8.8.3.5 Derivation Process of Boundary Filtering Strength

Inputs to this process are:

-   -   a picture sample array recPicture,    -   a location (xCb, yCb) specifying the top-left sample of the        current coding block relative to the top-left sample of the        current picture,    -   a variable nCbW specifying the width of the current coding        block,    -   a variable nCbH specifying the height of the current coding        block,    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered,    -   a variable cIdx specifying the colour component of the current        coding block,    -   a two-dimensional (nCbW)×(nCbH) array edge Flags.        Output of this process is a two-dimensional (nCbW)×(nCbH) array        b S specifying the boundary filtering strength.        . . .        For xD_(i) with i=0 . . . xN and yD_(j) with j=0 . . . yN, the        following applies:    -   If edge Flags[xD_(i)][yD_(j)] is equal to 0, the variable        bS[xD_(i)][yD_(j)] is set equal to 0.    -   Otherwise, the following applies:        -   . . .        -   The variable bS[xD_(i)][yD_(j)] is derived as follows:            -   If cIdx is equal to 0 and both samples p₀ and q₀ are in                a coding block with intra_bdpcm_flag equal to 1,                bS[xD_(i)][yD_(j)] is set equal to 0.            -   Otherwise, if the sample p₀ or q₀ is in the coding block                of a coding unit coded with intra prediction mode,                bS[xD_(i)][yD_(j)] is set equal to 2.            -   Otherwise, if the block edge is also a transform block                edge and the sample p₀ or q₀ is in a coding block with                ciip_flag equal to 1, bS[xD_(i)][yD_(j)] is set equal to                2.            -   Otherwise, if the block edge is also a transform block                edge and the sample p₀ or q₀ is in a transform block                which contains one or more non-zero transform                coefficient levels, bS[xD_(i)][yD_(j)] is set equal to                1.            -   [[Otherwise, if the block edge is also a transform block                edge, cIdx is greater than 0, and the sample p₀ or q₀ is                in a transform unit with tu_joint_cbcr_residual_flag                equal to 1, bS[xD_(i)][yD_(j)] is set equal to 1.]]            -   Otherwise, if the prediction mode of the coding subblock                containing the sample p₀ is different from the                prediction mode of the coding subblock containing the                sample q₀ (i.e. one of the coding subblock is coded in                IBC prediction mode and the other is coded in inter                prediction mode), bS[xD_(i)][yD_(j)] is set equal to 1            -   Otherwise, if cIdx is equal to 0 and one or more of the                following conditions are true, bS[xD_(i)][yD_(j)] is set                equal to 1:                -   The coding subblock containing the sample p₀ and the                    coding subblock containing the sample q₀ are both                    coded in IBC prediction mode, and the absolute                    difference between the horizontal or vertical                    component of the block vectors used in the                    prediction of the two coding subblocks is greater                    than or equal to 8 in units of 1/16 luma samples.                -   For the prediction of the coding subblock containing                    the sample p₀ different reference pictures or a                    different number of motion vectors are used than for                    the prediction of the coding subblock containing the                    sample q₀.                -    NOTE 1—The determination of whether the reference                    pictures used for the two coding subblocks are the                    same or different is based only on which pictures                    are referenced, without regard to whether a                    prediction is formed using an index into reference                    picture list 0 or an index into reference picture                    list 1, and also without regard to whether the index                    position within a reference picture list is                    different.                -   NOTE 2—The number of motion vectors that are used                    for the prediction of a coding subblock with                    top-left sample covering (xSb, ySb), is equal to                    PredFlagL0[xSb][ySb]+PredFlagL1[xSb][ySb].                -   One motion vector is used to predict the coding                    subblock containing the sample p₀ and one motion                    vector is used to predict the coding subblock                    containing the sample q₀, and the absolute                    differencebetweenthehorizontalorverticalcomponentofthemotionvectorsusedis                    greater than or equal to 8 in units of 1/16 luma                    samples.                -   Two motion vectors and two different reference                    pictures are used to predict the coding subblock                    containing the sample p₀, two motion vectors for the                    same two reference pictures are used to predict the                    coding subblock containing the sample q₀ and the                    absolute difference between the horizontal or                    vertical component of the two motion vectors used in                    the prediction of the two coding subblocks for the                    same reference picture is greater than or equal to 8                    in units of 1/16 luma samples.                -   Two motion vectors for the same reference picture                    are used to predict the coding subblock containing                    the sample p₀, two motion vectors for the same                    reference picture are used to predict the coding                    subblock containing the sample q₀ and both of the                    following conditions are true:                -    The absolute difference between the horizontal or                    vertical component of list 0 motion vectors used in                    the prediction of the two coding subblocks is                    greater than or equal to 8 in 1/16 luma samples, or                    the absolute difference between the horizontal or                    vertical component of the list 1 motion vectors used                    in the prediction of the two coding subblocks is                    greater than or equal to 8 in units of 1/16 luma                    samples.                -    The absolute difference between the horizontal or                    vertical component of list 0 motion vector used in                    the prediction of the coding subblock containing the                    sample p₀ and the list 1 motion vector used in the                    prediction of the coding subblock containing the                    sample q0 is greater than or equal to 8 in units of                    1/16 luma samples, or the absolute difference                    between the horizontal or vertical component of the                    list 1 motion vector used in the prediction of the                    coding subblock containing the sample p₀ and list 0                    motion vector used in the prediction of the coding                    subblock containing the sample q₀ is greater than or                    equal to 8 in units of 1/16 luma samples.            -   Otherwise, the variable bS[xD_(i)][yD_(j)] is set equal                to 0.

5.4. Embodiment #4 on Luma Deblocking Filtering Process

8.8.3.6.1 Decision Process for Luma Block Edges

Inputs to this process are:

-   -   a picture sample array recPicture,    -   a location (xCb, yCb) specifying the top-left sample of the        current coding block relative to the top-left sample of the        current picture,    -   a location (xBl, yBl) specifying the top-left sample of the        current block relative to the top-left sample of the current        coding block,    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered,    -   a variable bS specifying the boundary filtering strength,    -   a variable maxFilterLengthP specifying the max filter length,    -   a variable maxFilterLengthQ specifying the max filter length.        Outputs of this process are:    -   the variables dE, dEp and dEq containing decisions,    -   the modified filter length variables maxFilterLengthP and        maxFilterLengthQ,    -   the variable t_(C).        . . .        The following ordered steps apply:

. . .

-   -   1. When sidePisLargeBlk or sideQisLargeBIk is greater than 0,        the following applies:        -   a. The variables dp0L, dp3L are derived and maxFilterLengthP            is modified as follows:            -   [[If sidePisLargeBlk is equal to 1, the following                applies:                dp0L=(dp0+Abs(p _(5,0)−2*p _(4,0) +p                _(3,0))+1)>>1  (8-1087)                dp3L=(dp3+Abs(p _(5,3)−2*p _(4,3) +p                _(3,3))+1)>>1  (8-1088)            -   Otherwise, the following applies:]]                dp0L=dp0  (8-1089)                dp3L=dp3  (8-1090)                [[maxFilterLengthP=3  (8-1091)]]        -   b. The variables dq0L and dq3L are derived as follows:            -   [[If sideQisLargeBlk is equal to 1, the following                applies:                dq0L=(dq0+Abs(q _(5,0)−2*q _(4,0) +q                _(3,0))+1)>>1  (8-1092)                dq3L=(dq3+Abs(q _(5,3)−2*q _(4,3) +q                _(3,3))+1)>>1  (8-1093)            -   Otherwise, the following applies:]]                dq0L=dq0  (8-1094)                dq3L=dq3  (8-1095)

. . .

-   -   2. The variables dE, dEp and dEq are derived as follows:        -   . . .

5.5. Embodiment #5 on Chroma Deblocking Filtering Process

8.8.3.6.3 Decision Process for Chroma Block Edges

This process is only invoked when ChromaArrayType is not equal to 0.

Inputs to this process are:

-   -   a chroma picture sample array recPicture,

    -   a chroma location (xCb, yCb) specifying the top-left sample of        the current chroma coding block relative to the top-left chroma        sample of the current picture,

    -   a chroma location (xBl, yBl) specifying the top-left sample of        the current chroma block relative to the top-left sample of the        current chroma coding block,

    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered,

    -   a variable cIdx specifying the colour component index,

    -   a variable cQpPicOffset specifying the picture-level chroma        quantization parameter offset,

    -   a variable bS specifying the boundary filtering strength,

    -   a variable maxFilterLengthCbCr.        Outputs of this process are

    -   the modified variable maxFilterLengthCbCr,

    -   the variable t_(C).        The variable maxK is derived as follows:

    -   If edgeType is equal to EDGE_VER, the following applies:        maxK=(SubHeightC==1)?3:1  (8-1124)

    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        maxK=(SubWidthC==1)?3:1  (8-1125)        The values p_(i) and q_(i) with i=0 . . . maxFilterLengthCbCr        and k=0 . . . maxK are derived as follows:

    -   If edgeType is equal to EDGE_VER, the following applies:        q _(i,k)=recPicture[xCb+xBl+i][yCb+yBl+k]  (8-1126)        p _(i,k)=recPicture[xCb+xBl−i−1][yCb+yBl+k]  (8-1127)        subSampleC=SubHeightC  (8-1128)

    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        q _(i,k)=recPicture[xCb+xBl+k][yCb+yBl+i]  (8-1129)        p _(i,k)=recPicture[xCb+xBl+k][yCb+yBl−i−1]  (8-1130)        subSampleC=SubWidthC  (8-1131)

    -   

    -   

    -           The value of the variable β is determined as specified in Table        t-18 based on the quantization parameter Q derived as follows:        Q=Clip3(0,63,Qp_(C)+(slice_beta_offset_div2<<1))  (8-1134)        where slice_beta_offset_div2 is the value of the syntax element        slice_beta_offset_div2 for the slice that contains sample        q_(0,0).        The variable β is derived as follows:        β=β′*(1<<(BitDepth_(C)−8))  (8-1135)        The value of the variable t_(C)′ is determined as specified in        Table 8-18 based on the chroma quantization parameter Q derived        as follows:        Q=Clip3(0,65,Qp_(C)+2*(bS−1)+(slice_tc_offset_div2<<1))  (8-1136)        where slice_tc_offset_div2 is the value of the syntax element        slice_tc_offset_div2 for the slice that contains sample q_(0,0).        The variable t_(C) is derived as follows:        t _(C)=(BitDepth_(C)<10)?(t _(C)′+2)>>(10−BitDepth_(C)):t        _(C)′*(1<<(BitDepth_(C)−8))  (8-1137)        When maxFilterLengthCbCr is equal to 1 and bS is not equal to 2,        maxFilterLengthCbCr is set equal to 0.

5.6. Embodiment #6 on Chroma QP in Deblocking

8.8.3.6.3 Decision Process for Chroma Block Edges

This process is only invoked when ChromaArrayType is not equal to 0.

Inputs to this process are:

-   -   a chroma picture sample array recPicture,    -   a chroma location (xCb, yCb) specifying the top-left sample of        the current chroma coding block relative to the top-left chroma        sample of the current picture,    -   a chroma location (xBl, yBl) specifying the top-left sample of        the current chroma block relative to the top-left sample of the        current chroma coding block,    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered,    -   a variable cIdx specifying the colour component index,    -   a variable cQpPicOffset specifying the picture-level chroma        quantization parameter offset,    -   a variable bS specifying the boundary filtering strength,    -   a variable maxFilterLengthCbCr.        Outputs of this process are    -   the modified variable maxFilterLengthCbCr,    -   the variable t_(C).        The variable maxK is derived as follows:    -   If edgeType is equal to EDGE_VER, the following applies:        maxK=(SubHeightC==1)?3:1  (8-1124)    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        maxK=(SubWidthC==1)?3:1  (8-1125)        The values p_(i) and q_(i) with i=0 . . . maxFilterLengthCbCr        and k=0 . . . maxK are derived as follows:    -   If edgeType is equal to EDGE_VER, the following applies:        q _(i,k)=recPicture[xCb+xBl+i][yCb+yBl+k]  (8-1126)        p _(i,k)=recPicture[xCb+xBl−i−1][yCb+yBl+k]  (8-1127)        subSampleC=SubHeightC  (8-1128)    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        q _(i,k)=recPicture[xCb+xBl+k][yCb+yBl+i]  (8-1129)        p _(i,k)=recPicture[xCb+xBl+k][yCb+yBl−i−1]  (8-1130)        subSampleC=SubWidthC  (8-1131)        The variables Qp_(Q) and Qp_(P) are set equal to the Qp_(Y)        values of the coding units which include the coding blocks        containing the sample q_(0,0) and p_(0,0), respectively.        The variable Qp_(C) is derived as follows:        [[qPi=Clip3(0,63,((Qp_(Q)+Qp_(P)+1)>>1)+cQpPicOffset)  (8-1132)]]        Qp_(C)=ChromaQpTable[cIdx−1][qPi]  (8-1133)    -   NOTE—The variable cQpPicOffset provides an adjustment for the        value of pps_cb_qp_offset or pps_cr_qp_offset, according to        whether the filtered chroma component is the Cb or Cr component.        However, to avoid the need to vary the amount of the adjustment        within the picture, the filtering process does not include an        adjustment for the value of slice_cb_qp_offset or        slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is        equal to 1) for the value of CuQpOffset_(Cb), CuQpOffset_(Cr),        or CuQpOffset_(CbCr).

5.7. Embodiment #7 on Chroma QP in Deblocking

8.8.3.6.3 Decision Process for Chroma Block Edges

This process is only invoked when Chroma Array Type is not equal to 0.

Inputs to this process are:

-   -   a chroma picture sample array recPicture,    -   a chroma location (xCb, yCb) specifying the top-left sample of        the current chroma coding block relative to the top-left chroma        sample of the current picture,    -   . . .        Outputs of this process are    -   the modified variable maxFilterLengthCbCr,    -   the variable t_(C).        The variable maxK is derived as follows:    -   If edgeType is equal to EDGE_VER, the following applies:        maxK=(SubHeightC==1)?3:1  (8-1124)    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        maxK=(SubWidthC==1)?3:1  (8-1125)        The values p_(i) and q_(i) with i=0 . . . maxFilterLengthCbCr        and k=0 . . . maxK are derived as follows:    -   If edgeType is equal to EDGE_VER, the following applies:        q _(i,k)=recPicture[xCb+xBl+i][yCb+yBl+k]  (8-1126)        p _(i,k)=recPicture[xCb+xBl−i−1][yCb+yBl+k]  (8-1127)        subSampleC=SubHeightC  (8-1128)    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        q _(i,k)=recPicture[xCb+xBl+k][yCb+yBl+i]  (8-1129)        p _(i,k)=recPicture[xCb+xBl+k][yCb+yBl−i−1]  (8-1130)        subSampleC=SubWidthC  (8-1131)        [[The variables Qp_(Q) and Qp_(P) are set equal to the Qp_(Y)        values of the coding units which include the coding blocks        containing the sample q_(0,0) and p_(0,0), respectively.        The variable Qp_(C) is derived as follows:        qPi=Clip3(0,63,((Qp_(Q)+Qp_(P)+1)>>1)+cQpPicOffset)  (8-1132)        Qp_(C)=ChomaQpTable[cIdx−1][qPi]  (8-1133)    -   NOTE—The variable cQpPicOffset provides an adjustment for the        value of pps_cb_qp_offset or pps_cr_qp_offset, according to        whether the filtered chroma component is the Cb or Cr component.        However, to avoid the need to vary the amount of the adjustment        within the picture, the filtering process does not include an        adjustment for the value of slice_cb_qp_offset or        slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is        equal to 1) for the value of CuQpOffset_(Cb), CuQpOffset_(Cr),        or CuQpOffset_(CbCr).        The value of the variable β′ is determined as specified in Table        8-18 based on the quantization parameter Q derived as follows:        Q=Clip3(0,63,Qp_(C)+(slice_beta_offset_div2<<1))  (8-1134)        where slice_beta_offset_div2 is the value of the syntax element        slice_beta_offset_div2 for the slice that contains sample        q_(0,0).        The variable β is derived as follows:        β=β′*(1<<(BitDepth_(C)−8))  (8-1135)        The value of the variable t_(C)′ is determined as specified in        Table 8-18 based on the chroma quantization parameter Q derived        as follows:        Q=Clip3(0,65,Qp_(C)+2*(bS−1)+(slice_tc_offset_div2<<1))  (8-1136)        where slice_tc_offset_div2 is the value of the syntax element        slice_tc_offset_div2 for the slice that contains sample q_(0,0).

5.8. Embodiment #8 on Chroma QP in Deblocking

When making filter decisions for the depicted three samples (with solidcircles), the QPs of the luma CU that covers the center position of thechroma CU including the three samples is selected. Therefore, for the1^(st), 2^(nd), and 3^(rd) chroma sample (depicted in FIG. 11 ), onlythe QP of CU_(Y)3 is utilized, respectively.

In this way, how to select luma CU for chromaquantization/dequantization process is aligned with that for chromafilter decision process.

5.9. Embodiment #9 on QP Used for JCCR Coded Blocks

8.7.3 Scaling process for Transform Coefficients

Inputs to this process are:

-   -   a luma location (xTbY, yTbY) specifying the top-left sample of        the current luma transform block relative to the top-left luma        sample of the current picture,    -   a variable nTbW specifying the transform block width,    -   a variable nTbH specifying the transform block height,    -   a variable cIdx specifying the colour component of the current        block,    -   a variable bitDepth specifying the bit depth of the current        colour component.        Output of this process is the (nTbW)×(nTbH) array d of scaled        transform coefficients with elements d[x][y]. The quantization        parameter qP is derived as follows:    -   If cIdx is equal to 0 and transform_skip_flag[xTbY][yTbY] is        equal to 0, the following applies:        qP=Qp′_(Y)  (8-950)    -   Otherwise, if cIdx is equal to 0 (and        transform_skip_flag[xTbY][yTbY] is equal to 1), the following        applies:        qP=Max(QpPrimeTsMin,Qp′_(Y))  (8-951)    -   Otherwise, if TuCResMode[xTbY][yTbY] is unequal to 0 [[equal to        2]], the following applies:        qP=Qp′_(CbCr)  (8-952)    -   Otherwise, if cIdx is equal to 1, the following applies:        qP=Qp′_(Cb)  (8-953)    -   Otherwise (cIdx is equal to 2), the following applies:        qP=Qp′_(Cr)  (8-954)

5.10 Embodiment #10 on QP Used for JCCR Coded Blocks

8.8.3.2 Deblocking Filter Process for One Direction

Inputs to this process are:

-   -   the variable treeType specifying whether the luma        (DUAL_TREE_LUMA) or chroma components (DUAL_TREE_CHROMA) are        currently processed,

    -   when treeType is equal to DUAL_TREE_LUMA, the reconstructed        picture prior to deblocking, i.e., the array recPicture_(L),

    -   when ChromaArrayType is not equal to 0 and treeType is equal to        DUAL_TREE_CHROMA, the arrays recPicture_(Cb) and        recPicture_(Cr),

    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered.        Outputs of this process are the modified reconstructed picture        after deblocking, i.e:

    -   when treeType is equal to DUAL_TREE_LUMA, the array        recPicture_(L),

    -   when ChromaArrayType is not equal to 0 and treeType is equal to        DUAL_TREE_CHROMA, the arrays recPicture_(Cb) and        recPicture_(Cr).        The variables first CompIdx and last CompIdx are derived as        follows:        firstCompIdx=(treeType==DUAL_TREE_CHROMA)?1:0  (8-1022)        lastCompIdx=(treeType==DUAL_TREE_LUMA∥ChromaArrayType==0)?0:2  (8-1023)        For each coding unit and each coding block per colour component        of a coding unit indicated by the colour component index cIdx        ranging from firstCompIdx to lastCompIdx, inclusive, with coding        block width nCbW, coding block height nCbH and location of        top-left sample of the coding block (xCb, yCb),when cIdx is        equal to 0, or when cIdx is not equal to 0 and edgeType is equal        to EDGE_VER and xCb % 8 is equal 0, or when cIdx is not equal to        0 and edgeType is equal to EDGE_HOR and yCb % 8 is equal to 0,        the edges are filtered by the following ordered steps:        . . .        [[5. The picture sample array recPicture is derived as follows:

    -   If cIdx is equal to 0, recPicture is set equal to the        reconstructed luma picture sample array prior to deblocking        recPicture_(L).

    -   Otherwise, if cIdx is equal to 1, recPicture is set equal to the        reconstructed chroma picture sample array prior to deblocking        recPicture_(Cb).

    -   Otherwise (cIdx is equal to 2), recPicture is set equal to the        reconstructed chroma picture sample array prior to deblocking        recPicture_(Cr)]]

    -   

    -   

    -   

    -   The edge filtering process for one direction is invoked for a        coding block as specified in clause 8.8.3.6 with the variable        edgeType, the variable cIdx, the reconstructed picture prior to        deblocking recPicture, the location (xCb, yCb), the coding block        width nCbW, the coding block height nCbH, and the arrays bS,        maxFilterLengthPs, and maxFilterLengthQs, as inputs, and the        modified reconstructed picture recPicture as output.        8.8.3.5 Derivation Process of Boundary Filtering Strength        Inputs to this process are:

    -   a picture sample array recPicture,

    -   a location (xCb, yCb) specifying the top-left sample of the        current coding block relative to the top-left sample of the        current picture,

    -   a variable nCbW specifying the width of the current coding        block,

    -   a variable nCbH specifying the height of the current coding        block,

    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered,

    -   a variable cIdx specifying the colour component of the current        coding block,

    -   a two-dimensional (nCbW)×(nCbH) array edgeFlags.        Output of this process is a two-dimensional (nCbW)×(nCbH) array        bS specifying the boundary filtering strength.        The variables xD_(i), yD_(j), xN and yN are derived as follows:        . . .        For xD_(i) with i=0 . . . xN and yD_(j) with j=0 . . . yN, the        following applies:

    -   If edgeFlags[xD_(i)][yD_(j)] is equal to 0, the variable        bS[xD_(i)][yD_(j)] is set equal to 0.

    -   Otherwise, the following applies:        -   The sample values p₀ and q₀ are derived as follows:            -   If edgeType is equal to EDGE_VER, p₀ is set equal to                recPicturecIdx                xCb+xD_(i)−1][yCb+yD_(j)] and q₀ is set equal to                recPicture                [xCb+xD_(i)][yCb+yD_(j)].            -   Otherwise (edgeType is equal to EDGE_HOR), p₀ is set                equal to recPicturecIdx                [xCb+xD_(i)][yCb+yD_(j)−1] and q₀ is set equal to                recPicture                [xCb+xD_(i)][yCb+yD_(j)].                . . .                8.8.3.6 Edge Filtering Process for One Direction                Inputs to this process are:

    -   a variable edgeType specifying whether vertical edges (EDGE_VER)        or horizontal edges (EDGE_HOR) ae currently processed,

    -   a variable cIdx specifying the current colour component,

    -   the reconstructed picture prior to deblocking recPicture,

    -   a location (xCb, yCb) specifying the top-left sample of the        current coding block relative to the top-left sample of the        current picture,

    -   a variable nCbW specifying the width of the current coding        block,

    -   a variable nCbH specifying the height of the current coding        block,

    -   the array bS specifying the boundary strength,

    -   the arrays maxFilterLengthPs and maxFilterLengthQs.        Output of this process is the modified reconstructed picture        after deblocking recPicture_(i).        . . .

    -   Otherwise (cIdx is not equal to 0), the filtering process for        edges in the chroma coding block of current coding unit        specified by cIdx consists of the following ordered steps:        -   1. The variable cQpPicOffset is derived as follows:

        -   

        -   3. The decision process for chromablock edges as specified            in clause 8.8.3.6.3 is invoked with the chroma picture            sample array recPicture, the location of the chroma coding            block (xCb, yCb), the location of the chroma block (xBl,            yBl) set equal to (xD_(k), yD_(m)), the edge direction            edgeType,            the variable cQpPicOffset, the boundary filtering strength            bS[xD_(k)][yD_(m)], and the variable maxFilterLengthCbCr set            equal to maxFilterLengthPs[xD_(k)][yD_(m)] as inputs, and            the modified variable maxFilterLengthCbCr, and the variable            t_(C) as outputs.

        -   4. When maxFilterLengthCbCr is greater than 0, the filtering            process for chroma block edges as specified in clause            8.8.3.6.4 is invoked with the chroma picture sample array            recPicture, the location of the chroma coding block (xCb,            yCb), the chroma location of the block (xBl, yBl) set equal            to xD_(k), yD_(m)), the edge direction edgeType, the            variable maxFilterLengthCbC            and the variable t_(C) as inputs, and the modified chroma            picture sample array recPicture as output.

        -               8.8.3.6.3 Decision Process for Chromablock Edges            This process is only invoked when ChromaArrayType is not            equal to 0.            Inputs to this process are:

    -   a chroma picture sample array recPicture,

    -   a chroma location (xCb, yCb) specifying the top-left sample of        the current chroma coding block relative to the top-left chroma        sample of the current picture,

    -   a chroma location (xBl, yBl) specifying the top-left sample of        the current chroma block relative to the top-left sample of the        current chroma coding block,

    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered,

    -   [[a variable cIdx specifying the colour component index,]]

    -   a variable cQpPicOffset specifying the picture-level chroma        quantization parameter offset,

    -   a variable bS specifying the boundary filtering strength,

    -   a variable maxFilterLengthCbCr.        Outputs of this process are

    -   the modified variable maxFilterLengthCbCr,

    -   the variable t_(C).        The variable maxK is derived as follows:

    -   If edgeType is equal to EDGE_VER, the following applies:        maxK=(SubHeightC==1)?3:1  (8-1124)

    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        maxK=(SubWidthC==1)?3:1  (8-1125)        The values p_(i) and q_(i) with        i=0 . . . maxFilterLengthCbCr and k=0 . . . maxK are derived as        follows:

    -   If edgeType is equal to EDGE_VER, the following applies:        q        =recPicture        [xCb+xBl+i][yCb+yBl+k]  (8-1126)        p        =recPicture        [xCb+xBl−i−1][yCb+yBl+k]  (8-1127)        subSampleC=SubHeightC  (8-1128)

    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        q        =recPicture        [xCb+xBl+k][yCb+yBl+i]  (8-1129)        p        =recPicture        [xCb+xBl+k][yCb+yBl−i−1]  (8-1130)        subSampleC=SubWidthC  (8-1131)        The variables Qp_(Q) and Qp_(P) are set equal to the Qp_(Y)        values of the coding units which include the coding blocks        containing the sample q_(0,0) and p_(0,0), respectively.

The variable Qp_(C) is derived as follows:qPi=

(Qp_(Q)+Qp_(P)+1)>>1

  (8-1132)

-   -   NOTE—The variable cQpPicOffset provides an adjustment for the        value of pps_cb_qp_offset or pps_cr_qp_offset, according to        whether the filtered chroma component is the Cb or Cr component.        However, to avoid the need to vary the amount of the adjustment        within the picture, the filtering process does not include an        adjustment for the value of slice_cb_qp_offset or        slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is        equal to 1) for the value of CuQpOffset_(Cb), CuQpOffset_(Cr),        or CuQpOffset_(CbCr).        The value of the variable β′ is determined as specified in Table        8-18 based on the quantization parameter Q derived as follows:        Q=Clip3(0,63,Qp_(C)+(slice_beta_offset_div2<<1))  (8-1134)        where slice_beta_offset_div2 is the value of the syntax element        slice_beta_offset_div2 for the slice that contains sample        q_(0,0).        The variable β is derived as follows:        β=β′*(1<<(BitDepth_(C)−8))  (8-1135)        The value of the variable t_(C)′ is determined as specified in        Table 8-18 based on the chroma quantization parameter Q derived        as follows:        Q=Clip3(0,65,Qp_(C)+2*(bS−1)+(slice_tc_offset_div2<<1))  (8-1136)        where slice_tc_offset_div2 is the value of the syntax element        slice_tc_offset_div2 for the slice that contains sample q_(0,0).        The variable t_(C) is derived as follows:        t _(C)=(BitDepth_(C)<10)?(t _(C)′+2)>>(10−BitDepth_(C)):t        _(C)′*(1<<(BitDepth_(C)−8))  (8-1137)        When maxFilterLengthCbCr is equal to 1 and bS is not equal to 2,        maxFilterLengthCbCr is set equal to 0.        When maxFilterLengthCbCr is equal to 3, the following ordered        steps apply:        1. The variables n1, dpq0        , dpq1        , dp        , dq        and d        are derived as follows:        n1=(subSampleC==2)?1:3  (8-1138)        dp0        =Abs(p        _(2,0)−2*p        _(1,0) +p        _(0,0))  (8-1139)        dp1        =Abs(p        _(2,n1)−2*p        _(1,n1) +p        _(0,n1))  (8-1140)        dq0        =Abs(q        _(2,0)−2*q        _(1,0) +q        _(0,0))  (8-1141)        dq1        =Abs(q        _(2,n1)−2*q        _(1,n1) +q        _(0,n1))  (8-1142)        dpq0        =dp0        +dq0          (8-1143)        dpq1        =dp1        +dq1          (8-1144)        dp        =dp0        +dp1          (8-1145)        dq        =dq0        +dq1          (8-1146)        d        =dpq0        +dpq1          (8-1147)        3. The variables dSam0 and dSam1 are both set equal to 0.        4. When d is less than, the following ordered steps apply:    -   a. The variable dpq is set equal to 2*dpq0.    -   b. The variable dSam0 is derived by invoking the decision        process for a chroma sample as specified in cause 8.8.3.6.8 for        the sample location (xCb+xBl, yCb+yBl) with sample values        p_(0,0), p_(3,0), q_(0,0), and q_(3,0), the variables dpq, β and        t_(C) as inputs, and the output is assigned to the decision        dSam0.    -   c. The variable dpq is set equal to 2*dpq1.    -   d. The variable dSam1 is modified as follows:        -   If edgeType is equal to EDGE_VER, for the sample location            (xCb+xBl, yCb+yBl+n1), the decision process for a chroma            sample as specified in clause 8.8.3.6.8 is invoked with            sample values p_(0,n1), p_(3,n1), q_(0,n1), and q_(3,n1),            the variables dpq, β and t_(C) as inputs, and the output is            assigned to the decision dSam1.        -   Otherwise (edgeType is equal to EDGE_HOR),for the sample            location (xCb+xBl+n1, yCb+yBl), the decision process for a            chroma sample as specified in clause 8.8.3.6.8 is invoked            with sample values p_(0,n1), p_(3,n1), q_(0,n1) and            q_(3,n1), the variables dpq, β and t_(C) as inputs, and the            output is assigned to the decision dSam1.            5. The variable maxFilterLengthCbCr is modified as follows:    -   If dSam0 is equal to 1 and dSam1 is equal to 1,        maxFilterLengthCbCr is set equal to 3.    -   Otherwise, maxFilterLengthCbCr is set equal to 1.        8.8.3.6.4 Filtering Process for Chroma Block Edges        This process is only invoked when ChromaArrayType is not equal        to 0.        Inputs to this process are:    -   a chroma picture sample array recPicture,    -   a chroma location (xCb, yCb) specifying the top-left sample of        the current chroma coding block relative to the top-left chroma        sample of the current picture,    -   a chroma location (xBl, yBl) specifying the top-left sample of        the current chroma block relative to the top-left sample of the        current chroma coding block,    -   a variable edgeType specifying whether a vertical (EDGE_VER) or        a horizontal (EDGE_HOR) edge is filtered,    -   a variable maxFilterLengthCbCr containing the maximum chroma        filter length,    -   the variable t_(C).        Output of this process is the modified chroma picture sample        array recPicture.        . . .        The values p_(i) and q_(i) with i=0 . . . maxFilterLengthCbCr        and k=0 . . . maxK are derived as follows:    -   If edgeType is equal to EDGE_VER, the following applies:        q _(i,k)=recPicture        [xCb+xBl+i][yCb+yBl+k]  (8-1150)        p _(i,k)=recPicture        [xCb+xBl−i−1][yCb+yBl+k]  (8-1151)    -   Otherwise (edgeType is equal to EDGE_HOR), the following        applies:        q _(i,k)=recPicture        [xCb+xBl+k][yCb+yBl+i]  (8-1152)        p _(i,k)=recPicture        [xCb+xBl+k][yCb+yBl−i−1]  (8-1153)        Depending on the value of edgeType, the following applies:    -   If edgeType is equal to EDGE_VER, for each sample location        (xCb+xBl, yCb+yBl+k), k=0 . . . maxK, the following ordered        steps apply:    -   1. The filtering process for a chroma sample as specified in        clause 8.8.3.6.9 is invoked with the variable        maxFilterLengthCbCr, the sample values p_(i,k), q_(i,k) with i=0        . . . maxFilterLengthCbCr, the locations (xCb+xBl−i−1,        yCb+yBl+k) and (xCb+xBl+i, yCb+yBl+k) with i=0 . . .        maxFilterLengthCbCr−1, and the variable t_(C) as inputs, and the        filtered sample values p_(i)′ and q_(i)′ with i=0 . . .        maxFilterLengthCbCr−1 as outputs.    -   2. The filtered sample values p_(i)′ and q_(i)′ with i=0 . . .        maxFilterLengthCbCr−1 replace the corresponding samples inside        the sample array recPicture as follows:        recPicture        [xCb+xBl+i][yCb+yBl+k]=q _(i)′  (8-1154)        recPicturec        [xCb+xBl−i−1][yCb+yBl+k]=p _(i)′  (8-1155)    -   Otherwise (edgeType is equal to EDGE_HOR), for each sample        location (xCb+xBl+k, yCb+yBl), k=0 . . . maxK, the following        ordered steps apply:    -   1. The filtering process for a chroma sample as specified in        clause 8.8.3.6.9 is invoked with the variable        maxFilterLengthCbCr, the sample values p_(i,k), q_(i,k), with        i=0 . . . maxFilterLengthCbCr, the locations (xCb+xBl+k,        yCb+yBl−i−1) and (xCb+xBl+k, yCb+yBl+i), and the variable t_(C)        as inputs, and the filtered sample values p_(i)′ and q_(i)′ as        outputs.    -   2. The filtered sample values p_(i)′ and q_(i)′ replace the        corresponding samples inside the sample array recPicture as        follows:        recPicturce        [xCb+xBl+k][yCb+yBl+i]=q _(i)′        recPicture        [xCb+xBl+k][yCb+yBl−i−1]p _(i)′  (8-1156)

5.11 Embodiment #11

8.8.3.6.3 Decision process for chroma block edges

. . .

[[The variables Qp_(Q) and Qp_(P) are set equal to the Qp_(Y) values ofthe coding units which include the coding blocks containing the sampleq_(0,0) and p_(0,0), respectively.

The variable Qp_(C) is derived as follows:qPi=Clip3(0,63,((Qp_(Q)+Qp_(P)+1)>>1)+cQpPicOffset)  (8-1132)QpC=ChromaOpTable[cIdx−1][QpI]  (8-1133)]]

-   -   

    -   

    -   

5.12 Embodiment #12

8.8.3.6.3 Decision Process for Chroma Block Edges

. . .

[[The variables Qp_(Q) and Qp_(P) are set equal to the Qp_(Y) values ofthe coding units which include the coding blocks containing the sampleq_(0,0) and p_(0,0), respectively.

The variable Qp_(c) is derived as follows:qPi=Clip3(0,63,((Qp_(Q)+Qp_(P)+1)>>1)+cQpPicOffset)  (8-1132)Qp_(c)=ChromaQpTable[cIdx−1][qPi]  (8-1133)

-   -   NOTE—The variable cQpPicOffset provides an adjustment for the        value of pps_cb_qp_offset or pps_cr_qp_offset, according to        whether the filtered chroma component is the Cb or Cr component.        However, to avoid the need to vaRy the amount of the adjustment        within the picture, the filtering process does not include an        adjustment for the value of slice_cb_qp_offset or        slice_cr_qp_offset nor (when cu_chroma_qp_offset_enabled_flag is        equal to 1) for the value of CuQpOffset_(Cb), CuQpOffset_(Cr),        or CuQpOffset_(CbCr).]]

6. Example Implementations of the Disclosed Technology

FIG. 12 is a block diagram of a video processing apparatus 1200. Theapparatus 1200 may be used to implement one or more of the methodsdescribed herein. The apparatus 1200 may be embodied in a smartphone,tablet, computer, Internet of Things (IoT) receiver, and so on. Theapparatus 1200 may include one or more processors 1202, one or morememories 1204 and video processing hardware 1206. The processor(s) 1202may be configured to implement one or more methods described in thepresent document. The memory (memories) 1204 may be used for storingdata and code used for implementing the methods and techniques describedherein. The video processing hardware 1206 may be used to implement, inhardware circuitry, some techniques described in the present document,and may be partly or completely be a part of the processors 1202 (e.g.,graphics processor core GPU or other signal processing circuitry).

In the present document, the term “video processing” may refer to videoencoding, video decoding, video compression or video decompression. Forexample, video compression algorithms may be applied during conversionfrom pixel representation of a video to a corresponding bitstreamrepresentation or vice versa. The bitstream representation of a currentvideo block may, for example, correspond to bits that are eitherco-located or spread in different places within the bitstream, as isdefined by the syntax. For example, a macroblock may be encoded in termsof transformed and coded error residual values and also using bits inheaders and other fields in the bitstream.

It will be appreciated that the disclosed methods and techniques willbenefit video encoder and/or decoder embodiments incorporated withinvideo processing devices such as smartphones, laptops, desktops, andsimilar devices by allowing the use of the techniques disclosed in thepresent document.

FIG. 13 is a flowchart for an example method 1300 of video processing.The method 1300 includes, at 1310, performing a conversion between avideo unit and a bitstream representation of the video unit, wherein,during the conversion, a deblocking filter is used on boundaries of thevideo unit such that when a chroma quantization parameter (QP) table isused to derive parameters of the deblocking filter,processingbythechromaQPtableisperformedonindividualchromaQPvalues.

Some embodiments may be described using the following clause-basedformat.

1. A method of video processing, comprising:

performing a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such that whena chroma quantization parameter (QP) table is used to derive parametersof the deblocking filter, processing by the chroma QP table is performedon individual chroma QP values.

2. The method of clause 1, wherein chroma QP offsets are added to theindividual chroma QP values subsequent to the processing by the chromaQP table.

3. The method of any of clauses 1-2, wherein the chroma QP offsets areadded to values outputted by the chroma QP table.

4. The method of any of clauses 1-2, wherein the chroma QP offsets arenot considered as input to the chroma QP table.

5. The method of clause 2, wherein the chroma QP offsets are at apicture-level or at a video unit-level.

6. A method of video processing, comprising:

performing a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein the chromaQP offsets are at picture/slice/tile/brick/subpicture level.

7. The method of clause 6, wherein the chroma QP offsets used in thedeblocking filter are associated with a coding method applied on aboundary of the video unit.

8. The method of clause 7, wherein the coding method is a joint codingof chrominance residuals (JCCR) method.

9. A method of video processing, comprising:

performing a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein informationpertaining to a same luma coding unit is used in the deblocking filterand for deriving a chroma QP offset.

10. The method of clause 9, wherein the same luma coding unit covers acorresponding luma sample of a center position of the video unit,wherein the video unit is a chroma coding unit.

11. The method of clause 9, wherein a scaling process is applied to thevideo unit, and wherein one or more parameters of the deblocking filterdepend at least in part on quantization/dequantization parameters of thescaling process.

12. The method of clause 11, wherein the quantization/dequantizationparameters of the scaling process include the chroma QP offset.

13. The method of any of clauses 9-12, wherein the luma sample in thevideo unit is in the P side or Q side.

14. The method of clause 13, wherein the information pertaining to thesame luma coding unit depends on a relative position of the coding unitwith respect to the same luma coding unit.

15. A method of video processing, comprising:

performing a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein anindication of enabling usage of the chroma QP offsets is signaled in thebitstream representation.

16. The method of clause 15, wherein the indication is signaledconditionally in response to detecting one or more flags.

17. The method of clause 16, wherein the one or more flags are relatedto a JCCR enabling flag or a chroma QP offset enabling flag.

18. The method of clause 15, wherein the indication is signaled based ona derivation.

19. A method of video processing, comprising:

performing a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein the chromaQP offsets used in the deblocking filter are identical of whether JCCRcoding method is applied on a boundary of the video unit or a methoddifferent from the JCCR coding method is applied on the boundary of thevideo unit.

20. A method of video processing, comprising:

performing a conversion between a video unit and a bitstreamrepresentation of the video unit, wherein, during the conversion, adeblocking filter is used on boundaries of the video unit such thatchroma QP offsets are used in the deblocking filter, wherein a boundarystrength (BS) of the deblocking filter is calculated without comparingreference pictures and/or a number of motion vectors (MVs) associatedwith the video unit at a P side boundary with reference pictures and/ora number of motion vectors (MVs) associated with the video unit at a Qside.

21. The method of clause 20, wherein the deblocking filter is disabledunder one or more conditions.

22. The method of clause 21, wherein the one or more conditions areassociated with: a magnitude of the motion vectors (MVs) or a thresholdvalue.

23. The method of clause 22, wherein the threshold value is associatedwith at least one of: i. contents of the video unit, ii. a messagesignaled in DPS/SPS/VPS/PPS/APS/picture header/slice header/tile groupheader/Largest coding unit (LCU)/Coding unit (CU)/LCU row/group ofLCUs/TU/PU block/Video coding unit, iii. a position ofCU/PU/TU/block/Video coding unit, iv. a coded mode of blocks withsamples along the boundaries, v. a transform matrix applied to the videounits with samples along the boundaries, vi. a shape or dimension of thevideo unit, vii. an indication of a color format, viii. a coding treestructure, ix. a slice/tile group type and/or picture type, x. a colorcomponent, xi. a temporal layer ID, or xii. a profile/level/tier of astandard.

24. The method of clause 20, wherein different QP offsets are used forTS coded video units and non-TS coded video units.

25. The method of clause 20, wherein a QP used in a luma filtering stepis related to a QP used in a scaling process of a luma block.

26. A video decoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 25.

27. A video encoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 25.

28. A computer program product having computer code stored thereon, thecode, when executed by a processor, causes the processor to implement amethod recited in any of clauses 1 to 25.

29. A method, apparatus or system described in the present document.

FIG. 15 is a block diagram that illustrates an example video codingsystem 100 that may utilize the techniques of this disclosure.

As shown in FIG. 15 , video coding system 100 may include a sourcedevice 110 and a destination device 120. Source device 110 generatesencoded video data which may be referred to as a video encoding device.Destination device 120 may decode the encoded video data generated bysource device 110 which may be referred to as a video decoding device.

Source device 110 may include a video source 112, a video encoder 114,and an input/output (I/O) interface 116.

Video source 112 may include a source such as a video capture device, aninterface to receive video data from a video content provider, and/or acomputer graphics system for generating video data, or a combination ofsuch sources. The video data may comprise one or more pictures. Videoencoder 114 encodes the video data from video source 112 to generate abitstream. The bitstream may include a sequence of bits that form acoded representation of the video data. The bitstream may include codedpictures and associated data. The coded picture is a codedrepresentation of a picture. The associated data may include sequenceparameter sets, picture parameter sets, and other syntax structures. I/Ointerface 116 may include a modulator/demodulator (modem) and/or atransmitter. The encoded video data may be transmitted directly todestination device 120 via I/O interface 116 through network 130 a. Theencoded video data may also be stored onto a storage medium/server 130 bfor access by destination device 120.

Destination device 120 may include an I/O interface 126, a video decoder124, and a display device 122.

I/O interface 126 may include a receiver and/or a modem. I/O interface126 may acquire encoded video data from the source device 110 or thestorage medium/server 130 b. Video decoder 124 may decode the encodedvideo data. Display device 122 may display the decoded video data to auser. Display device 122 may be integrated with the destination device120, or may be external to destination device 120 which be configured tointerface with an external display device.

Video encoder 114 and video decoder 124 may operate according to a videocompression standard, such as the High Efficiency Video Coding (HEVC)standard, Versatile Video Coding (VVC) standard and other current and/orfurther standards.

FIG. 16 is a block diagram illustrating an example of video encoder 200,which may be video encoder 114 in the system 100 illustrated in FIG. 15.

Video encoder 200 may be configured to perform any or all of thetechniques of this disclosure. In the example of FIG. 16 , video encoder200 includes a plurality of functional components. The techniquesdescribed in this disclosure may be shared among the various componentsof video encoder 200. In some examples, a processor may be configured toperform any or all of the techniques described in this disclosure.

The functional components of video encoder 200 may include a partitionunit 201, a predication unit 202 which may include a mode select unit203, a motion estimation unit 204, a motion compensation unit 205 and anintra prediction unit 206, a residual generation unit 207, a transformunit 208, a quantization unit 209, an inverse quantization unit 210, aninverse transform unit 211, a reconstruction unit 212, a buffer 213, andan entropy encoding unit 214.

In other examples, video encoder 200 may include more, fewer, ordifferent functional components. In an example, predication unit 202 mayinclude an intra block copy (IBC) unit. The IBC unit may performpredication in an IBC mode in which at least one reference picture is apicture where the current video block is located.

Furthermore, some components, such as motion estimation unit 204 andmotion compensation unit 205 may be highly integrated, but arerepresented in the example of FIG. 5 separately for purposes ofexplanation.

Partition unit 201 may partition a picture into one or more videoblocks. Video encoder 200 and video decoder 300 may support variousvideo block sizes.

Mode select unit 203 may select one of the coding modes, intra or inter,e.g., based on error results, and provide the resulting intra- orinter-coded block to a residual generation unit 207 to generate residualblock data and to a reconstruction unit 212 to reconstruct the encodedblock for use as a reference picture. In some example, Mode select unit203 may select a combination of intra and inter predication (CIIP) modein which the predication is based on an inter predication signal and anintra predication signal. Mode select unit 203 may also select aresolution for a motion vector (e.g, a sub-pixel or integer pixelprecision) for the block in the case of inter-predication.

To perform inter prediction on a current video block, motion estimationunit 204 may generate motion information for the current video block bycomparing one or more reference frames from buffer 213 to the currentvideo block. Motion compensation unit 205 may determine a predictedvideo block for the current video block based on the motion informationand decoded samples of pictures from buffer 213 other than the pictureassociated with the current video block.

Motion estimation unit 204 and motion compensation unit 205 may performdifferent operations for a current video block, for example, dependingon whether the current video block is in an I slice, a P slice, or a Bslice.

In some examples, motion estimation unit 204 may perform uni-directionalprediction for the current video block, and motion estimation unit 204may search reference pictures of list 0 or list 1 for a reference videoblock for the current video block. Motion estimation unit 204 may thengenerate a reference index that indicates the reference picture in list0 or list 1 that contains the reference video block and a motion vectorthat indicates a spatial displacement between the current video blockand the reference video block. Motion estimation unit 204 may output thereference index, a prediction direction indicator, and the motion vectoras the motion information of the current video block. Motioncompensation unit 205 may generate the predicted video block of thecurrent block based on the reference video block indicated by the motioninformation of the current video block.

In other examples, motion estimation unit 204 may perform bi-directionalprediction for the current video block, motion estimation unit 204 maysearch the reference pictures in list 0 for a reference video block forthe current video block and may also search the reference pictures inlist 1 for another reference video block for the current video block.Motion estimation unit 204 may then generate reference indexes thatindicate the reference pictures in list 0 and list 1 containing thereference video blocks and motion vectors that indicate spatialdisplacements between the reference video blocks and the current videoblock. Motion estimation unit 204 may output the reference indexes andthe motion vectors of the current video block as the motion informationof the current video block. Motion compensation unit 205 may generatethe predicted video block of the current video block based on thereference video blocks indicated by the motion information of thecurrent video block.

In some examples, motion estimation unit 204 may output a full set ofmotion information for decoding processing of a decoder.

In some examples, motion estimation unit 204 may do not output a fullset of motion information for the current video. Rather, motionestimation unit 204 may signal the motion information of the currentvideo block with reference to the motion information of another videoblock. For example, motion estimation unit 204 may determine that themotion information of the current video block is sufficiently similar tothe motion information of a neighboring video block.

In one example, motion estimation unit 204 may indicate, in a syntaxstructure associated with the current video block, a value thatindicates to the video decoder 300 that the current video block has thesame motion information as the another video block.

In another example, motion estimation unit 204 may identify, in a syntaxstructure associated with the current video block, another video blockand a motion vector difference (MVD). The motion vector differenceindicates a difference between the motion vector of the current videoblock and the motion vector of the indicated video block. The videodecoder 300 may use the motion vector of the indicated video block andthe motion vector difference to determine the motion vector of thecurrent video block.

As discussed above, video encoder 200 may predictively signal the motionvector. Two examples of predictive signaling techniques that may beimplemented by video encoder 200 include advanced motion vectorpredication (AMVP) and merge mode signaling.

Intra prediction unit 206 may perform intra prediction on the currentvideo block. When intra prediction unit 206 performs intra prediction onthe current video block, intra prediction unit 206 may generateprediction data for the current video block based on decoded samples ofother video blocks in the same picture. The prediction data for thecurrent video block may include a predicted video block and varioussyntax elements.

Residual generation unit 207 may generate residual data for the currentvideo block by subtracting (e.g., indicated by the minus sign) thepredicted video block(s) of the current video block from the currentvideo block. The residual data of the current video block may includeresidual video blocks that correspond to different sample components ofthe samples in the current video block.

In other examples, there may be no residual data for the current videoblock for the current video block, for example in a skip mode, andresidual generation unit 207 may not perform the subtracting operation.

Transform processing unit 208 may generate one or more transformcoefficient video blocks for the current video block by applying one ormore transforms to a residual video block associated with the currentvideo block.

After transform processing unit 208 generates a transform coefficientvideo block associated with the current video block, quantization unit209 may quantize the transform coefficient video block associated withthe current video block based on one or more quantization parameter (QP)values associated with the current video block.

Inverse quantization unit 210 and inverse transform unit 211 may applyinverse quantization and inverse transforms to the transform coefficientvideo block, respectively, to reconstruct a residual video block fromthe transform coefficient video block. Reconstruction unit 212 may addthe reconstructed residual video block to corresponding samples from oneor more predicted video blocks generated by the predication unit 202 toproduce a reconstructed video block associated with the current blockfor storage in the buffer 213.

After reconstruction unit 212 reconstructs the video block, loopfiltering operation may be performed reduce video blocking artifacts inthe video block.

Entropy encoding unit 214 may receive data from other functionalcomponents of the video encoder 200. When entropy encoding unit 214receives the data, entropy encoding unit 214 may perform one or moreentropy encoding operations to generate entropy encoded data and outputa bitstream that includes the entropy encoded data.

FIG. 17 is a block diagram illustrating an example of video decoder 300which may be video decoder 114 in the system 100 illustrated in FIG. 15.

The video decoder 300 may be configured to perform any or all of thetechniques of this disclosure. In the example of FIG. 17 , the videodecoder 300 includes a plurality of functional components. Thetechniques described in this disclosure may be shared among the variouscomponents of the video decoder 300. In some examples, a processor maybe configured to perform any or all of the techniques described in thisdisclosure.

In the example of FIG. 17 , video decoder 300 includes an entropydecoding unit 301, a motion compensation unit 302, an intra predictionunit 303, an inverse quantization unit 304, an inverse transformationunit 305, and a reconstruction unit 306 and a buffer 307. Video decoder300 may, in some examples, perform a decoding pass generally reciprocalto the encoding pass described with respect to video encoder 200 (e.g.,FIG. 16 ).

Entropy decoding unit 301 may retrieve an encoded bitstream. The encodedbitstream may include entropy coded video data (e.g., encoded blocks ofvideo data). Entropy decoding unit 301 may decode the entropy codedvideo data, and from the entropy decoded video data, motion compensationunit 302 may determine motion information including motion vectors,motion vector precision, reference picture list indexes, and othermotion information. Motion compensation unit 302 may, for example,determine such information by performing the AMVP and merge mode.

Motion compensation unit 302 may produce motion compensated blocks,possibly performing interpolation based on interpolation filters.Identifiers for interpolation filters to be used with sub-pixelprecision may be included in the syntax elements.

Motion compensation unit 302 may use interpolation filters as used byvideo encoder 20 during encoding of the video block to calculateinterpolated values for sub-integer pixels of a reference block. Motioncompensation unit 302 may determine the interpolation filters used byvideo encoder 200 according to received syntax information and use theinterpolation filters to produce predictive blocks.

Motion compensation unit 302 may uses some of the syntax information todetermine sizes of blocks used to encode frame(s) and/or slice(s) of theencoded video sequence, partition information that describes how eachmacroblock of a picture of the encoded video sequence is partitioned,modes indicating how each partition is encoded, one or more referenceframes (and reference frame lists) for each inter-encoded block, andother information to decode the encoded video sequence.

Intra prediction unit 303 may use intra prediction modes for examplereceived in the bitstream to form a prediction block from spatiallyadjacent blocks. Inverse quantization unit 303 inverse quantizes, i.e.,de-quantizes, the quantized video block coefficients provided in thebitstream and decoded by entropy decoding unit 301. Inverse transformunit 303 applies an inverse transform.

Reconstruction unit 306 may sum the residual blocks with thecorresponding prediction blocks generated by motion compensation unit202 or intra-prediction unit 303 to form decoded blocks. If desired, adeblocking filter may also be applied to filter the decoded blocks inorder to remove blockiness artifacts. The decoded video blocks are thenstored in buffer 307, which provides reference blocks for subsequentmotion compensation.

FIG. 18 is a block diagram showing an example video processing system1800 in which various techniques disclosed herein may be implemented.Various implementations may include some or all of the components of thesystem 1800. The system 1800 may include input 1802 for receiving videocontent. The video content may be received in a raw or uncompressedformat, e.g, 8 or 10 bit multi-component pixel values, or may be in acompressed or encoded format. The input 1802 may represent a networkinterface, a peripheral bus interface, or a storage interface. Examplesof network interface include wired interfaces such as Ethernet, passiveoptical network (PON), etc. and wireless interfaces such as Wi-Fi orcellular interfaces.

The system 1800 may include a coding component 1804 that may implementthe various coding or encoding methods described in the presentdocument. The coding component 1804 may reduce the average bitrate ofvideo from the input 1802 to the output of the coding component 1804 toproduce a coded representation of the video. The coding techniques aretherefore sometimes called video compression or video transcodingtechniques. The output of the coding component 1804 may be eitherstored, or transmitted via a communication connected, as represented bythe component 1806. The stored or communicated bitstream (or coded)representation of the video received at the input 1802 may be used bythe component 1808 for generating pixel values or displayable video thatis sent to a display interface 1810. The process of generatinguser-viewable video from the bitstream representation is sometimescalled video decompression. Furthermore, while certain video processingoperations are referred to as “coding” operations or tools, it will beappreciated that the coding tools or operations are used at an encoderand corresponding decoding tools or operations that reverse the resultsof the coding will be performed by a decoder.

Examples of a peripheral bus interface or a display interface mayinclude universal serial bus (USB) or high definition multimediainterface (HDMI) or Displayport, and so on. Examples of storageinterfaces include SATA (serial advanced technology attachment), PCI,IDE interface, and the like. The techniques described in the presentdocument may be embodied in various electronic devices such as mobilephones, laptops, smartphones or other devices that are capable ofperforming digital data processing and/or video display.

FIG. 19 is a flowchart representation of a method for video processingin accordance with the present technology. The method 1900 includes, atoperation 1910, determining, for a conversion between a chroma block ofa video and a bitstream representation of the video, applicability of adeblocking filter process to at least some samples at an edge of thechroma block based on a mode of joint coding of chroma residuals for thechroma block. The method 1900 also includes, at operation 1920,performing the conversion based on the determining.

In some embodiments, a value indicating the mode of the joint coding ofchroma residuals is equal to 2. In some embodiments, the deblockingfilter process further uses one or more quantization parameter offsetsat a video unit level, the video unit comprising a picture, a slice, atile, a brick, or a subpicture.

FIG. 20 is a flowchart representation of a method for video processingin accordance with the present technology. The method 2000 includes, atoperation 2010, determining, for a conversion between a current block ofa video and a bitstream representation of the video, a chromaquantization parameter used in a deblocking filtering process applied toat least some samples at an edge of the current block based oninformation of a corresponding transform block of the current block. Themethod 2000 also includes, at operation 2020, performing the conversionbased on the determining.

In some embodiments, the chroma quantization parameter is used fordeblocking samples along a first side of the edge of the current block,and the chroma quantization parameter is based on a mode of thetransform block that are on the first side. In some embodiments, thefirst side is referred to as P-side, the P-side comprising sampleslocated above the edge in case the edge is a horizontal boundary or tothe left of the edge in case the edge is a vertical boundary. In someembodiments, the chroma quantization parameter is used for deblockingsamples along a second side of the edge of the current block, and thechroma quantization parameter is based on a mode of the transform blockthat are on the second side. In some embodiments, the second side isreferred to as Q-side, the Q-side comprising samples located below theedge in case the edge is a horizontal boundary or to the right of theedge in case the edge is a vertical boundary.

In some embodiments, the chroma quantization parameter is determinedbased on whether a mode of joint coding of chroma residuals is applied.In some embodiments, the chroma quantization parameter is determinedbased on whether a mode of the joint coding of chroma residuals is equalto 2.

FIG. 21 is a flowchart representation of a method for video processingin accordance with the present technology. The method 2100 includes, atoperation 2110, performing a conversion between a current block of avideo and a bitstream representation of the video. During theconversion, a first chroma quantization parameter used in a deblockingfiltering process applied to at least some samples along an edge of thecurrent block is based on a second chroma quantization parameter used ina scaling process and a quantization parameter offset associated with abit depth.

In some embodiments, the first chroma quantization parameter is equal tothe second quantization parameter used in the scaling process minus thequantization parameter offset associated with the bit depth. In someembodiments, the first chroma quantization parameter used for deblockingsamples along a first side of the edge of the current block. In someembodiments, the first side is referred to as P-side, the P-sidecomprising samples located above the edge in case the edge is ahorizontal boundary or to the left of the edge in case the boundary is avertical boundary. In some embodiments, the first chroma quantizationparameter used for deblocking samples along a second side of the edge ofthe current block. In some embodiments, the second side is referred toas Q-side, the Q-side comprising samples located below the edge in casethe edge is a horizontal boundary or to the right of the edge in casethe edge is a vertical boundary.

In some embodiments, the first chroma quantization parameter is equal tothe second quantization parameter for a joint coding of chroma residualsused in the scaling process minus quantization parameter offsetassociated with the bit depth. In some embodiments, the first chromaquantization parameter is equal to the second quantization parameter fora chroma Cb component used in the scaling process minus quantizationparameter offset associated with the bit depth. In some embodiments, thefirst chroma quantization parameter is equal to the second quantizationparameter for a chroma Cr component used in the scaling process minusquantization parameter offset associated with the bit depth.

FIG. 22 is a flowchart representation of a method for video processingin accordance with the present technology. The method 2200 includes, atoperation 2210, performing a conversion between a video comprising oneor more coding units and a bitstream representation of the video. Thebitstream representation conforms to a format rule that specifies thatchroma quantization parameters are included in the bitstreamrepresentation at a coding unit level or a transform unit levelaccording to the format rule.

In some embodiments, the format rule specifies that the chromaquantization parameter is included at a coding unit level in case a sizeof the coding unit is larger than a virtual pipeline data unit. In someembodiments, the format rule specifies that the chroma quantizationparameter is included at a transform unit level in case a size of thecoding unit is larger than or equal to a virtual pipeline data unit. Insome embodiments, the format rule specifies that the chroma quantizationparameter is included at a coding unit level in case a size of thecoding unit is larger than a maximum transform block size. In someembodiments, the format rule specifies that the chroma quantizationparameter is included at a transform unit level in case a size of thecoding unit is larger than or equal to a maximum transform block size.In some embodiments, the format rule further specifies that whether ajoint coding of chroma residuals mode is applicable to a first codingunit of the one or more coding units is indicated at a coding unitlevel. In some embodiments, a transform block within the first codingunit inherits information about whether the joint coding of chromaresiduals mode is applicable at the first coding unit level.

FIG. 23 is a flowchart representation of a method for video processingin accordance with the present technology. The method 2300 includes, atoperation 2310, performing a conversion between a block of a video and abitstream representation of the video. The bitstream representationconforms to a format rule specifying that whether a joint coding ofchroma residuals mode is applicable to the block is indicated at acoding unit level in the bitstream representation.

In some embodiments, during the conversion, a transform block within acoding unit inherits information about whether the joint coding ofchroma residuals mode is applicable at the coding unit level.

In some embodiments, the conversion includes encoding the video into thebitstream representation. In some embodiments, the conversion includesdecoding the bitstream representation into the video.

Some embodiments of the disclosed technology include making a decisionor determination to enable a video processing tool or mode. In anexample, when the video processing tool or mode is enabled, the encoderwill use or implement the tool or mode in the processing of a block ofvideo, but may not necessarily modify the resulting bitstream based onthe usage of the tool or mode. That is, a conversion from the block ofvideo to the bitstream representation of the video will use the videoprocessing tool or mode when it is enabled based on the decision ordetermination. In another example, when the video processing tool ormode is enabled, the decoder will process the bitstream with theknowledge that the bitstream has been modified based on the videoprocessing tool or mode. That is, a conversion from the bitstreamrepresentation of the video to the block of video will be performedusing the video processing tool or mode that was enabled based on thedecision or determination.

Some embodiments of the disclosed technology include making a decisionor determination to disable a video processing tool or mode. In anexample, when the video processing tool or mode is disabled, the encoderwill not use the tool or mode in the conversion of the block of video tothe bitstream representation of the video. In another example, when thevideo processing tool or mode is disabled, the decoder will process thebitstream with the knowledge that the bitstream has not been modifiedusing the video processing tool or mode that was enabled based on thedecision or determination.

The disclosed and other solutions, examples, embodiments, modules andthe functional operations described in this document can be implementedin digital electronic circuitry, or in computer software, firmware, orhardware, including the structures disclosed in this document and theirstructural equivalents, or in combinations of one or more of them. Thedisclosed and other embodiments can be implemented as one or morecomputer program products, i.e., one or more modules of computer programinstructions encoded on a computer readable medium for execution by, orto control the operation of, data processing apparatus. The computerreadable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, a composition ofmatter effecting a machine-readable propagated signal, or a combinationof one or more them. The term “data processing apparatus” encompassesall apparatus, devices, and machines for processing data, including byway of example a programmable processor, a computer, or multipleprocessors or computers. The apparatus can include, in addition tohardware, code that creates an execution environment for the computerprogram in question, e.g., code that constitutes processor firmware, aprotocol stack, a database management system, an operating system, or acombination of one or more of them. A propagated signal is anartificially generated signal, e.g., a machine-generated electrical,optical, or electromagnetic signal, that is generated to encodeinformation for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this document can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random-access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Computer readable media suitable for storingcomputer program instructions and data include all forms of non-volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks;magneto optical disks; and CD ROM and DVD-ROM disks. The processor andthe memory can be supplemented by, or incorporated in, special purposelogic circuitry.

While this patent document contains many specifics, these should not beconstrued as limitations on the scope of any subject matter or of whatmay be claimed, but rather as descriptions of features that may bespecific to particular embodiments of particular techniques. Certainfeatures that are described in this patent document in the context ofseparate embodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described in this patent document should not be understoodas requiring such separation in all embodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document.

What is claimed is:
 1. A method of processing video data, comprising:performing a conversion between a video comprising one or more codingunits and a bitstream of the video, wherein the bitstream conforms to aformat rule that specifies that for a chroma block of a first codingunit of the one or more coding units, chroma quantization parameters areallowed to be included in the bitstream at a block level according tothe format rule; and wherein the format rule further specifies thatwhether a joint coding mode for chroma Cb residuals and chroma Crresiduals is applicable to the first coding unit is indicated at atransform unit level.
 2. The method of claim 1, wherein the format rulespecifies that for the chroma block, the chroma quantization parametersare allowed to be included at the block level in case a height or awidth of the first coding unit is larger than a size of a virtualpipeline data unit.
 3. The method of claim 2, wherein the block level isa coding unit level or the transform unit level.
 4. The method of claim1, wherein a first chroma quantization parameter used in a deblockingfiltering process applied to at least some samples along an edge of thefirst coding unit based on a second chroma quantization parameter usedin a scaling process and a quantization parameter offset associated witha bit depth of the video, wherein the scaling process comprises:applying a quantization on at least some coefficients representing acurrent block during encoding; or applying a dequantization on at leastsome coefficients from the bitstream during decoding.
 5. The method ofclaim 4, wherein the first chroma quantization parameter is equal to asecond quantization parameter used in the scaling process minus thequantization parameter offset associated with the bit depth of thevideo.
 6. The method of claim 4, wherein in case a value of a firstvariable indicating the joint coding mode for chroma Cb residuals andchroma Cr residuals being equal to 2, the first chroma quantizationparameter is equal to a third quantization parameter for the jointcoding mode for chroma Cb residuals and chroma Cr residuals used in thescaling process minus quantization parameter offset associated with thebit depth of the video.
 7. The method of claim 1, wherein the conversionincludes encoding the video into the bitstream.
 8. The method of claim1, wherein the conversion includes decoding the video from thebitstream.
 9. An apparatus for processing video data comprising aprocessor and a non-transitory memory with instructions thereon, whereinthe instructions upon execution by the processor, cause the processorto: perform a conversion between a video comprising one or more codingunits and a bitstream of the video, wherein the bitstream conforms to aformat rule that specifies that for a chroma block of a first codingunit of the one or more coding units, chroma quantization parameters areallowed to be included in the bitstream at a block level according tothe format rule; and wherein the format rule further specifies thatwhether a joint coding mode for chroma Cb residuals and chroma Crresiduals is applicable to the first coding unit is indicated at atransform unit level.
 10. The apparatus of claim 9, wherein the formatrule specifies that for the chroma block, the chroma quantizationparameters are allowed to be included at the block level in case aheight or a width of the first coding unit is larger than a size of avirtual pipeline data unit; and wherein the block level is a coding unitlevel or the transform unit level.
 11. The apparatus of claim 10,wherein a first chroma quantization parameter used in a deblockingfiltering process applied to at least some samples along an edge of thefirst coding unit based on a second chroma quantization parameter usedin a scaling process and a quantization parameter offset associated witha bit depth of the video, and wherein the scaling process comprises:applying a quantization on at least some coefficients representing acurrent block during encoding; or applying a dequantization on at leastsome coefficients from the bitstream during decoding; wherein the firstchroma quantization parameter is equal to a second quantizationparameter used in the scaling process minus the quantization parameteroffset associated with the bit depth of the video; and wherein in case avalue of a first variable indicating the joint coding mode for chroma Cbresiduals and chroma Cr residuals being equal to 2, the first chromaquantization parameter is equal to a third quantization parameter forthe joint coding mode for chroma Cb residuals and chroma Cr residualsused in the scaling process minus quantization parameter offsetassociated with the bit depth of the video.
 12. A non-transitorycomputer-readable storage medium storing instructions that cause aprocessor to: perform a conversion between a video comprising one ormore coding units and a bitstream of the video, wherein the bitstreamconforms to a format rule that specifies that for a chroma block of afirst coding unit of the one or more coding units, chroma quantizationparameters are allowed to be included in the bitstream at a block levelaccording to the format rule; and wherein the format rule furtherspecifies that whether a joint coding mode for chroma Cb residuals andchroma Cr residuals is applicable to the first coding unit is indicatedat a transform unit level.
 13. The non-transitory computer-readablestorage medium of claim 12, wherein the format rule specifies that forthe chroma block, the chroma quantization parameters are allowed to beincluded at the block level in case a height or a width of the firstcoding unit is larger than a size of a virtual pipeline data unit;wherein the block level is a coding unit level or the transform unitlevel.
 14. The non-transitory computer-readable storage medium of claim13, wherein a first chroma quantization parameter used in a deblockingfiltering process applied to at least some samples along an edge of thefirst coding unit based on a second chroma quantization parameter usedin a scaling process and a quantization parameter offset associated witha bit depth of the video, and wherein the scaling process comprises:applying a quantization on at least some coefficients representing acurrent block during encoding; or applying a dequantization on at leastsome coefficients from the bitstream during decoding; wherein the firstchroma quantization parameter is equal to a second quantizationparameter used in the scaling process minus the quantization parameteroffset associated with the bit depth of the video; and wherein in case avalue of a first variable indicating the joint coding mode for chroma Cbresiduals and chroma Cr residuals being equal to 2, the first chromaquantization parameter is equal to a third quantization parameter forthe joint coding mode for chroma Cb residuals and chroma Cr residualsused in the scaling process minus quantization parameter offsetassociated with the bit depth of the video.
 15. A non-transitorycomputer-readable recording medium storing a bitstream of a video whichis generated by a method performed by a video processing apparatus,wherein the method comprises: generating the bitstream for the videowhich comprises one or more coding units, wherein the bitstream conformsto a format rule that specifies that for a chroma block of a firstcoding unit of the one or more coding units, chroma quantizationparameters are allowed to be included in the bitstream at a block levelaccording to the format rule; and wherein the format rule furtherspecifies that whether a joint coding mode for chroma Cb residuals andchroma Cr residuals is applicable to the first coding unit is indicatedat a transform unit level.
 16. The non-transitory computer-readablerecording medium of claim 15, wherein the format rule specifies that forthe chroma block, the chroma quantization parameters are allowed to beincluded at the block level in case a height or a width of the firstcoding unit is larger than a size of a virtual pipeline data unit;wherein the block level is a coding unit level or the transform unitlevel.
 17. The non-transitory computer-readable recording medium ofclaim 16, wherein a first chroma quantization parameter used in adeblocking filtering process applied to at least some samples along anedge of the first coding unit based on a second chroma quantizationparameter used in a scaling process and a quantization parameter offsetassociated with a bit depth of the video, and wherein the scalingprocess comprises: applying a quantization on at least some coefficientsrepresenting a current block during encoding; or applying adequantization on at least some coefficients from the bitstream duringdecoding; wherein the first chroma quantization parameter is equal to asecond quantization parameter used in the scaling process minus thequantization parameter offset associated with the bit depth of thevideo; and wherein in case a value of a first variable indicating thejoint coding mode for chroma Cb residuals and chroma Cr residuals beingequal to 2, the first chroma quantization parameter is equal to a thirdquantization parameter for the joint coding mode for chroma Cb residualsand chroma Cr residuals used in the scaling process minus quantizationparameter offset associated with the bit depth of the video.